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-<link rel="up" href="../chrono.html" title="Chapter 4. Boost.Chrono 1.2.1">
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+<link rel="up" href="../chrono.html" title="Chapter 6. Boost.Chrono 2.0.4">
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<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="chrono.users_guide"></a><a class="link" href="users_guide.html" title="User's Guide">User's Guide</a>
</h2></div></div></div>
-<div class="toc"><dl>
+<div class="toc"><dl class="toc">
<dt><span class="section"><a href="users_guide.html#chrono.users_guide.getting_started">Getting Started</a></span></dt>
<dt><span class="section"><a href="users_guide.html#chrono.users_guide.tutorial">Tutorial</a></span></dt>
<dt><span class="section"><a href="users_guide.html#chrono.users_guide.examples">Examples</a></span></dt>
<div class="titlepage"><div><div><h3 class="title">
<a name="chrono.users_guide.getting_started"></a><a class="link" href="users_guide.html#chrono.users_guide.getting_started" title="Getting Started">Getting Started</a>
</h3></div></div></div>
-<div class="toc"><dl>
+<div class="toc"><dl class="toc">
<dt><span class="section"><a href="users_guide.html#chrono.users_guide.getting_started.install">Installing
Chrono</a></span></dt>
<dt><span class="section"><a href="users_guide.html#chrono.users_guide.getting_started.hello_world__">Hello
</h4></div></div></div>
<h6>
<a name="chrono.users_guide.getting_started.install.h0"></a>
- <span><a name="chrono.users_guide.getting_started.install.getting__emphasis_role__bold__boost_chrono__emphasis__"></a></span><a class="link" href="users_guide.html#chrono.users_guide.getting_started.install.getting__emphasis_role__bold__boost_chrono__emphasis__">Getting
+ <span
class="phrase"><a name="chrono.users_guide.getting_started.install.getting__emphasis_role__bold__boost_chrono__emphasis__"></a></span><a class="link" href="users_guide.html#chrono.users_guide.getting_started.install.getting__emphasis_role__bold__boost_chrono__emphasis__">Getting
<span class="bold"><strong>Boost.Chrono</strong></span> </a>
</h6>
<p>
</p>
<h6>
<a name="chrono.users_guide.getting_started.install.h1"></a>
- <span><a name="chrono.users_guide.getting_started.install.where_to_install_boost_chrono__"></a></span><a class="link" href="users_guide.html#chrono.users_guide.getting_started.install.where_to_install_boost_chrono__">Where
+ <span
class="phrase"><a name="chrono.users_guide.getting_started.install.where_to_install_boost_chrono__"></a></span><a class="link" href="users_guide.html#chrono.users_guide.getting_started.install.where_to_install_boost_chrono__">Where
to install Boost.Chrono? </a>
</h6>
<p>
</p>
<h6>
<a name="chrono.users_guide.getting_started.install.h2"></a>
- <span><a name="chrono.users_guide.getting_started.install.building_boost_chrono_"></a></span><a class="link" href="users_guide.html#chrono.users_guide.getting_started.install.building_boost_chrono_">Building
+ <span
class="phrase"><a name="chrono.users_guide.getting_started.install.building_boost_chrono_"></a></span><a class="link" href="users_guide.html#chrono.users_guide.getting_started.install.building_boost_chrono_">Building
Boost.Chrono </a>
</h6>
<p>
<span class="bold"><strong>Boost.Chrono</strong></span> can be configured as a header-only
- library. When <a class="link" href="reference.html#chrono.reference.cpp0x.chrono_chrono_hpp.conf.header_only" title="How to Build Boost.Chrono as a Header Only Library?"><code class="computeroutput"><span class="identifier">BOOST_CHRONO_HEADER_ONLY</span></code></a> is defined
- the Boost.Chrono is a header-only library. Otherwise is not a header only
- library and you need to compile it and build the library before use, for
- example using:
+ library defining <a class="link" href="reference.html#chrono.reference.cpp0x.chrono_chrono_hpp.conf.header_only" title="How to Build Boost.Chrono as a Header Only Library?"><code class="computeroutput"><span class="identifier">BOOST_CHRONO_HEADER_ONLY</span></code></a>. However
+ Boost.Chrono depends on the non header-only library Boost.System, so that
+ you will need to link with boost_system.
+ </p>
+<p>
+ Boost.System has un undocumented feature (use of macro BOOST_ERROR_CODE_HEADER_ONLY)
+ to make it header only.
+ </p>
+<p>
+ If <a class="link" href="reference.html#chrono.reference.cpp0x.chrono_chrono_hpp.conf.header_only" title="How to Build Boost.Chrono as a Header Only Library?"><code class="computeroutput"><span class="identifier">BOOST_CHRONO_HEADER_ONLY</span></code></a> is not
+ defined you need to compile it and build the library before use, for example
+ using:
</p>
<pre class="programlisting"><span class="identifier">bjam</span> <span class="identifier">libs</span><span class="special">/</span><span class="identifier">chrono</span><span class="special">/</span><span class="identifier">build</span>
</pre>
<h6>
<a name="chrono.users_guide.getting_started.install.h3"></a>
- <span><a name="chrono.users_guide.getting_started.install.requirements"></a></span><a class="link" href="users_guide.html#chrono.users_guide.getting_started.install.requirements">Requirements</a>
+ <span
class="phrase"><a name="chrono.users_guide.getting_started.install.requirements"></a></span><a class="link" href="users_guide.html#chrono.users_guide.getting_started.install.requirements">Requirements</a>
</h6>
<p>
In particular, <span class="bold"><strong>Boost.Chrono</strong></span> depends on:
</p>
<div class="variablelist">
<p class="title"><b></b></p>
-<dl>
+<dl class="variablelist">
<dt><span class="term"><a href="http://www.boost.org/libs/config" target="_top"><span class="bold"><strong>Boost.Config</strong></span></a></span></dt>
<dd><p>
for configuration purposes, ...
</div>
<h6>
<a name="chrono.users_guide.getting_started.install.h4"></a>
- <span><a name="chrono.users_guide.getting_started.install.building_an_executable_that_uses_boost_chrono_"></a></span><a class="link" href="users_guide.html#chrono.users_guide.getting_started.install.building_an_executable_that_uses_boost_chrono_">Building
+ <span
class="phrase"><a name="chrono.users_guide.getting_started.install.building_an_executable_that_uses_boost_chrono_"></a></span><a class="link" href="users_guide.html#chrono.users_guide.getting_started.install.building_an_executable_that_uses_boost_chrono_">Building
an Executable that Uses Boost.Chrono </a>
</h6>
<p>
In addition to link with the <span class="bold"><strong>Boost.Chrono</strong></span>
library you need also to link with the <span class="bold"><strong>Boost.System</strong></span>
- library. Once <span class="bold"><strong>Boost.System</strong></span> will be configurable
- to be a header only using <code class="computeroutput"><span class="identifier">BOOST_SYSTEM_INLINED</span></code>
- you will no need to link with it.
+ library. If <span class="bold"><strong>Boost.System</strong></span> is configured
+ defining BOOST_ERROR_CODE_HEADER_ONLY you will no need to link with it
+ as the dependent part is header only then.
</p>
<h6>
<a name="chrono.users_guide.getting_started.install.h5"></a>
- <span><a name="chrono.users_guide.getting_started.install.exception_safety_"></a></span><a class="link" href="users_guide.html#chrono.users_guide.getting_started.install.exception_safety_">Exception
+ <span
class="phrase"><a name="chrono.users_guide.getting_started.install.exception_safety_"></a></span><a class="link" href="users_guide.html#chrono.users_guide.getting_started.install.exception_safety_">Exception
safety </a>
</h6>
<p>
</p>
<h6>
<a name="chrono.users_guide.getting_started.install.h6"></a>
- <span><a name="chrono.users_guide.getting_started.install.thread_safety_"></a></span><a class="link" href="users_guide.html#chrono.users_guide.getting_started.install.thread_safety_">Thread
+ <span
class="phrase"><a name="chrono.users_guide.getting_started.install.thread_safety_"></a></span><a class="link" href="users_guide.html#chrono.users_guide.getting_started.install.thread_safety_">Thread
safety </a>
</h6>
<p>
</p>
<h6>
<a name="chrono.users_guide.getting_started.install.h7"></a>
- <span><a name="chrono.users_guide.getting_started.install.tested_compilers_"></a></span><a class="link" href="users_guide.html#chrono.users_guide.getting_started.install.tested_compilers_">Tested
+ <span
class="phrase"><a name="chrono.users_guide.getting_started.install.tested_compilers_"></a></span><a class="link" href="users_guide.html#chrono.users_guide.getting_started.install.tested_compilers_">Tested
compilers </a>
</h6>
<p>
<p>
Windows with
</p>
-<div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem">
+<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">
MSVC 10.0
</li></ul></div>
<p>
- Cygwin 1.7 with
- </p>
-<div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem">
- GCC 4.3.4
- </li></ul></div>
-<p>
MinGW with
</p>
-<div class="itemizedlist"><ul class="itemizedlist" type="disc">
+<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
GCC 4.5.0
</li>
<li class="listitem">
GCC 4.6.0 -std=c++0x
</li>
+<li class="listitem">
+ GCC 4.8.0
+ </li>
+<li class="listitem">
+ GCC 4.8.0 -std=c++0x
+ </li>
</ul></div>
<p>
+ Ubuntu with * GCC 4.4.6 * GCC 4.4.6 -std=c++0x * GCC 4.5.4 * GCC 4.5.4
+ -std=c++0x * GCC 4.6.1 * GCC 4.6.1 -std=c++0x * Intel 12.1.3 * Intel 12.1.3
+ -std=c++0x
+ </p>
+<p>
OsX with
</p>
-<div class="itemizedlist"><ul class="itemizedlist" type="disc">
+<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
GCC 4.1.2
</li>
<li class="listitem">
- clang 1.6
+ GCC 4.6.2
+ </li>
+<li class="listitem">
+ GCC 4.6.2 -std=c++0x
</li>
<li class="listitem">
- clang 2.9
+ GCC 4.7.0
</li>
<li class="listitem">
- clang 2.9 -std=c++0x
+ GCC 4.7.0 -std=c++0x
+ </li>
+<li class="listitem">
+ GCC 4.7.1
+ </li>
+<li class="listitem">
+ GCC 4.7.1 -std=c++0x
+ </li>
+<li class="listitem">
+ GCC 4.7.2
+ </li>
+<li class="listitem">
+ GCC 4.7.2 -std=c++0x
+ </li>
+<li class="listitem">
+ GCC 4.8.0
+ </li>
+<li class="listitem">
+ GCC 4.8.0 -std=c++0x
+ </li>
+<li class="listitem">
+ GCC 4.8.1
+ </li>
+<li class="listitem">
+ GCC 4.8.1 -std=c++0x
+ </li>
+<li class="listitem">
+ clang 3.1
+ </li>
+<li class="listitem">
+ clang 3.1 -std=c++0x -stdlib=libc++
+ </li>
+<li class="listitem">
+ clang 3.2
+ </li>
+<li class="listitem">
+ clang 3.2 -std=c++11 -stdlib=libc++
</li>
</ul></div>
<p>
</p></td></tr>
</table></div>
</div>
-<div class="section">
-<div class="titlepage"><div><div><h4 class="title">
+<div class="section"><div class="titlepage"><div><div><h4 class="title">
<a name="chrono.users_guide.getting_started.hello_world__"></a><a class="link" href="users_guide.html#chrono.users_guide.getting_started.hello_world__" title="Hello World!">Hello
World! </a>
-</h4></div></div></div>
-<p>
- If all you want to do is to time a program's execution, here is a complete
- program:
- </p>
-<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">chrono</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span>
-<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">cmath</span><span class="special">></span>
-
-<span class="keyword">int</span> <span class="identifier">main</span><span class="special">()</span>
-<span class="special">{</span>
- <span class="identifier">boost</span><span class="special">::</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">system_clock</span><span class="special">::</span><span class="identifier">time_point</span> <span class="identifier">start</span> <span class="special">=</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">system_clock</span><span class="special">::</span><span class="identifier">now</span><span class="special">();</span>
-
- <span class="keyword">for</span> <span class="special">(</span> <span class="keyword">long</span> <span class="identifier">i</span> <span class="special">=</span> <span class="number">0</span><span class="special">;</span> <span class="identifier">i</span> <span class="special"><</span> <span class="number">10000000</span><span class="special">;</span> <span class="special">++</span><span class="identifier">i</span> <span class="special">)</span>
- <span class="identifier">std</span><span class="special">::</span><span class="identifier">sqrt</span><span class="special">(</span> <span class="number">123.456L</span> <span class="special">);</span> <span class="comment">// burn some time</span>
-
- <span class="identifier">boost</span><span class="special">::</span><span class="identifier">chrono</span><span class="special">::</span><a class="link" href="reference.html#chrono.reference.cpp0x.duration_hpp.duration" title="Class Template duration<>"><code class="computeroutput"><span class="identifier">duration</span></code></a><span class="special"><</span><span class="keyword">double</span><span class="special">></span> <span class="identifier">sec</span> <span class="special">=</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">system_clock</span><span class="special">::</span><span class="identifier">now</span><span class="special">()</span> <span class="special">-</span> <span class="identifier">start</span><span class="special">;</span>
- <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"took "</span> <span class="special"><<</span> <span class="identifier">sec</span><span class="special">.</span><span class="identifier">count</span><span class="special">()</span> <span class="special"><<</span> <span class="string">" seconds\n"</span><span class="special">;</span>
- <span class="keyword">return</span> <span class="number">0</span><span class="special">;</span>
-<span class="special">}</span>
-</pre>
-<p>
- Output was:
- </p>
-<pre class="programlisting"><span class="identifier">took</span> <span class="number">0.832</span> <span class="identifier">seconds</span>
-</pre>
-</div>
+</h4></div></div></div></div>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="chrono.users_guide.tutorial"></a><a class="link" href="users_guide.html#chrono.users_guide.tutorial" title="Tutorial">Tutorial</a>
</h3></div></div></div>
-<div class="toc"><dl>
+<div class="toc"><dl class="toc">
<dt><span class="section"><a href="users_guide.html#chrono.users_guide.tutorial.duration">Duration</a></span></dt>
<dt><span class="section"><a href="users_guide.html#chrono.users_guide.tutorial.clocks">Clocks</a></span></dt>
<dt><span class="section"><a href="users_guide.html#chrono.users_guide.tutorial.time_point">Time Point</a></span></dt>
<div class="titlepage"><div><div><h4 class="title">
<a name="chrono.users_guide.tutorial.duration"></a><a class="link" href="users_guide.html#chrono.users_guide.tutorial.duration" title="Duration">Duration</a>
</h4></div></div></div>
-<div class="toc"><dl>
+<div class="toc"><dl class="toc">
<dt><span class="section"><a href="users_guide.html#chrono.users_guide.tutorial.duration.so_what_exactly_is_a__duration__and_how_do_i_use_one_">So
What Exactly is a <code class="computeroutput"><span class="identifier">duration</span></code>
and How Do I Use One?</a></span></dt>
<p>
The library consists of six units of time <a class="link" href="reference.html#chrono.reference.cpp0x.duration_hpp.duration" title="Class Template duration<>"><code class="computeroutput"><span class="identifier">duration</span></code></a>:
</p>
-<div class="itemizedlist"><ul class="itemizedlist" type="disc">
+<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<a class="link" href="reference.html#chrono.reference.cpp0x.duration_hpp.duration_typedefs" title="duration typedefs"><code class="computeroutput"><span class="identifier">hours</span></code></a>
</li>
<p>
There are several options open to the user:
</p>
-<div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem">
+<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">
If the author of the function wants to accept any <a class="link" href="reference.html#chrono.reference.cpp0x.duration_hpp.duration" title="Class Template duration<>"><code class="computeroutput"><span class="identifier">duration</span></code></a>, and is willing
to work in floating-point <a class="link" href="reference.html#chrono.reference.cpp0x.duration_hpp.duration" title="Class Template duration<>"><code class="computeroutput"><span class="identifier">duration</span></code></a>s, he can simply
use any floating-point <a class="link" href="reference.html#chrono.reference.cpp0x.duration_hpp.duration" title="Class Template duration<>"><code class="computeroutput"><span class="identifier">duration</span></code></a> as the parameter:
<span class="identifier">f</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">microseconds</span><span class="special">(</span><span class="number">3</span><span class="special">));</span>
</pre>
-<div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem">
+<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">
If the author of the function wants to traffic only in integral
<a class="link" href="reference.html#chrono.reference.cpp0x.duration_hpp.duration" title="Class Template duration<>"><code class="computeroutput"><span class="identifier">duration</span></code></a>s, and is content
with handling nothing finer than say nanoseconds (just as an example),
</p>
<pre class="programlisting"><span class="identifier">f</span><span class="special">(</span><span class="identifier">s</span><span class="special">);</span> <span class="comment">// does not compile</span>
</pre>
-<div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem">
+<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">
If the author of the function wants to accept any <a class="link" href="reference.html#chrono.reference.cpp0x.duration_hpp.duration" title="Class Template duration<>"><code class="computeroutput"><span class="identifier">duration</span></code></a>, but wants to work
with integral representations and wants to control the rounding mode
internally, then he can template the function:
<span class="identifier">f</span><span class="special">(</span><span class="identifier">boost</span><span class="special">::</span><span class="identifier">chrono</span><span class="special">::</span><a class="link" href="reference.html#chrono.reference.cpp0x.duration_hpp.duration" title="Class Template duration<>"><code class="computeroutput"><span class="identifier">duration</span></code></a><span class="special"><</span><span class="keyword">double</span><span class="special">>(</span><span class="number">1.</span><span class="special">/</span><span class="number">3</span><span class="special">));</span>
</pre>
-<div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem">
+<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem">
If the author in the example does not want to accept floating-point
based <a class="link" href="reference.html#chrono.reference.cpp0x.duration_hpp.duration" title="Class Template duration<>"><code class="computeroutput"><span class="identifier">duration</span></code></a>s, he can enforce
that behavior like so:
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="chrono.users_guide.tutorial.duration.is_it_possible_for_the_user_to_pass_a___duration_to_a_function_with_the_units_being_ambiguous_"></a><a class="link" href="users_guide.html#chrono.users_guide.tutorial.duration.is_it_possible_for_the_user_to_pass_a___duration_to_a_function_with_the_units_being_ambiguous_" title="Is it possible for the user to pass a duration to a function with the units being ambiguous?">Is
- it possible for the user to pass a <a class="link" href="reference.html#chrono.reference.cpp0x.duration_hpp.duration" title="Class Template duration<>"><code class="computeroutput"><span class="identifier">duration</span></code></a> to a function with the
+ it possible for the user to pass a <code class="computeroutput"><span class="identifier">duration</span></code> to a function with the
units being ambiguous?</a>
</h5></div></div></div>
<p>
The standard defines three system-wide clocks that are associated to the
computer time.
</p>
-<div class="itemizedlist"><ul class="itemizedlist" type="disc">
+<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<a class="link" href="reference.html#chrono.reference.cpp0x.system_clocks_hpp.system_clock" title="Class system_clock"><code class="computeroutput"><span class="identifier">system_clock</span></code></a> represents system-wide
realtime clock that can be synchronized with an external clock.
<span class="keyword">typedef</span> <span class="identifier">an</span> <span class="identifier">instantiation</span> <span class="identifier">of</span> <span class="identifier">ratio</span> <span class="identifier">period</span><span class="special">;</span>
<span class="keyword">typedef</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">chrono</span><span class="special">::</span><a class="link" href="reference.html#chrono.reference.cpp0x.duration_hpp.duration" title="Class Template duration<>"><code class="computeroutput"><span class="identifier">duration</span></code></a><span class="special"><</span><span class="identifier">rep</span><span class="special">,</span> <span class="identifier">period</span><span class="special">></span> <a class="link" href="reference.html#chrono.reference.cpp0x.duration_hpp.duration" title="Class Template duration<>"><code class="computeroutput"><span class="identifier">duration</span></code></a><span class="special">;</span>
<span class="keyword">typedef</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">chrono</span><span class="special">::</span><a class="link" href="reference.html#chrono.reference.cpp0x.time_point_hpp.time_point" title="Class template time_point<>"><code class="computeroutput"><span class="identifier">time_point</span></code></a><span class="special"><</span><a class="link" href="reference.html#chrono.reference.cpp0x.clock" title="Clock Requirements"><code class="computeroutput"><span class="identifier">Clock</span></code></a><span class="special">></span> <span class="identifier">time_point</span><span class="special">;</span>
- <span class="keyword">static</span> <span class="identifier">constexpr</span> <span class="keyword">bool</span> <span class="identifier">is_steady</span> <span class="special">=</span> <span class="keyword">true</span> <span class="keyword">or</span> <span class="keyword">false</span><span class="special">;</span>
+ <span class="keyword">static</span> <span class="keyword">constexpr</span> <span class="keyword">bool</span> <span class="identifier">is_steady</span> <span class="special">=</span> <span class="keyword">true</span> <span class="keyword">or</span> <span class="keyword">false</span><span class="special">;</span>
<span class="keyword">static</span> <span class="identifier">time_point</span> <span class="identifier">now</span><span class="special">();</span>
<span class="special">};</span>
<div class="titlepage"><div><div><h4 class="title">
<a name="chrono.users_guide.tutorial.time_point"></a><a class="link" href="users_guide.html#chrono.users_guide.tutorial.time_point" title="Time Point">Time Point</a>
</h4></div></div></div>
-<div class="toc"><dl><dt><span class="section"><a href="users_guide.html#chrono.users_guide.tutorial.time_point.so_what_exactly_is_a__time_point__and_how_do_i_use_one_">So
+<div class="toc"><dl
class="toc"><dt><span class="section"><a href="users_guide.html#chrono.users_guide.tutorial.time_point.so_what_exactly_is_a__time_point__and_how_do_i_use_one_">So
What Exactly is a <code class="computeroutput"><span class="identifier">time_point</span></code>
and How Do I Use One?</a></span></dt></dl></div>
<p>
of saying the same thing, is that a <a class="link" href="reference.html#chrono.reference.cpp0x.time_point_hpp.time_point" title="Class template time_point<>"><code class="computeroutput"><span class="identifier">time_point</span></code></a> represents an epoch
plus or minus a <a class="link" href="reference.html#chrono.reference.cpp0x.duration_hpp.duration" title="Class Template duration<>"><code class="computeroutput"><span class="identifier">duration</span></code></a>. Examples of <a class="link" href="reference.html#chrono.reference.cpp0x.time_point_hpp.time_point" title="Class template time_point<>"><code class="computeroutput"><span class="identifier">time_point</span></code></a>s include:
</p>
-<div class="itemizedlist"><ul class="itemizedlist" type="disc">
+<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
3 minutes after the computer booted.
</li>
<a name="chrono.users_guide.tutorial.specific_clocks"></a><a class="link" href="users_guide.html#chrono.users_guide.tutorial.specific_clocks" title="Specific Clocks">Specific
Clocks</a>
</h4></div></div></div>
-<div class="toc"><dl>
+<div class="toc"><dl class="toc">
<dt><span class="section"><a href="users_guide.html#chrono.users_guide.tutorial.specific_clocks.system_clock">system_clock</a></span></dt>
<dt><span class="section"><a href="users_guide.html#chrono.users_guide.tutorial.specific_clocks.steady_clock">steady_clock</a></span></dt>
<dt><span class="section"><a href="users_guide.html#chrono.users_guide.tutorial.specific_clocks.high_resolution_clock">high_resolution_clock</a></span></dt>
<p>
Process and thread clocks are used usually to measure the time spent
by code blocks, as a basic time-spent profiling of different blocks of
- code (Boost.Stopwatch is a clear example of this use).
+ code (Boost.Chrono.Stopwatch is a clear example of this use).
</p>
</div>
<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="chrono.users_guide.tutorial.i_o"></a><a class="link" href="users_guide.html#chrono.users_guide.tutorial.i_o" title="I/O">I/O</a>
</h4></div></div></div>
+<div class="toc"><dl class="toc">
+<dt><span class="section"><a href="users_guide.html#chrono.users_guide.tutorial.i_o.duration_io">duration</a></span></dt>
+<dt><span class="section"><a href="users_guide.html#chrono.users_guide.tutorial.i_o.system_clock_time_point_io"><code class="computeroutput"><span class="identifier">system_clock</span><span class="special">::</span><span class="identifier">time_point</span></code></a></span></dt>
+<dt><span class="section"><a href="users_guide.html#chrono.users_guide.tutorial.i_o.other_clocks_time_point_io">Other
+ clocks time_point</a></span></dt>
+<dt><span class="section"><a href="users_guide.html#chrono.users_guide.tutorial.i_o.low_level_i_o">Low
+ level I/O</a></span></dt>
+</dl></div>
+<div class="section">
+<div class="titlepage"><div><div><h5 class="title">
+<a name="chrono.users_guide.tutorial.i_o.duration_io"></a><a class="link" href="users_guide.html#chrono.users_guide.tutorial.i_o.duration_io" title="duration">duration</a>
+</h5></div></div></div>
<p>
- Any <a class="link" href="reference.html#chrono.reference.cpp0x.duration_hpp.duration" title="Class Template duration<>"><code class="computeroutput"><span class="identifier">duration</span></code></a> can be streamed out to
- a <code class="computeroutput"><span class="identifier">basic_ostream</span></code>. The run-time
- value of the <a class="link" href="reference.html#chrono.reference.cpp0x.duration_hpp.duration" title="Class Template duration<>"><code class="computeroutput"><span class="identifier">duration</span></code></a> is formatted according
- to the rules and current format settings for <a class="link" href="reference.html#chrono.reference.cpp0x.duration_hpp.duration" title="Class Template duration<>"><code class="computeroutput"><span class="identifier">duration</span></code></a><code class="computeroutput"><span class="special">::</span><span class="identifier">rep</span></code>. This is followed by a single space
- and then the compile-time unit name of the <a class="link" href="reference.html#chrono.reference.cpp0x.duration_hpp.duration" title="Class Template duration<>"><code class="computeroutput"><span class="identifier">duration</span></code></a>. This unit name is built
- on the string returned from <code class="computeroutput"><span class="identifier">ratio_string</span><span class="special"><></span></code> and the data used to construct
- the <a class="link" href="reference.html#chrono.reference.io.chrono_io_hpp.duration_punct" title="Template Class duration_punct<>"><code class="computeroutput"><span class="identifier">duration_punct</span></code></a> which was inserted
- into the stream's locale. If a <a class="link" href="reference.html#chrono.reference.io.chrono_io_hpp.duration_punct" title="Template Class duration_punct<>"><code class="computeroutput"><span class="identifier">duration_punct</span></code></a> has not been inserted
- into the stream's locale, a default constructed <a class="link" href="reference.html#chrono.reference.io.chrono_io_hpp.duration_punct" title="Template Class duration_punct<>"><code class="computeroutput"><span class="identifier">duration_punct</span></code></a> will be added to
- the stream's locale.
- </p>
+ Any <a class="link" href="reference.html#chrono.reference.cpp0x.duration_hpp.duration" title="Class Template duration<>"><code class="computeroutput"><span class="identifier">duration</span></code></a> can be streamed out
+ to a <code class="computeroutput"><span class="identifier">basic_ostream</span></code>. The
+ run-time value of the <a class="link" href="reference.html#chrono.reference.cpp0x.duration_hpp.duration" title="Class Template duration<>"><code class="computeroutput"><span class="identifier">duration</span></code></a> is formatted according
+ to the rules and current format settings for <a class="link" href="reference.html#chrono.reference.cpp0x.duration_hpp.duration" title="Class Template duration<>"><code class="computeroutput"><span class="identifier">duration</span></code></a><code class="computeroutput"><span class="special">::</span><span class="identifier">rep</span></code> get_duration_style and the durationpunct
+ facet.
+ </p>
<p>
- <a class="link" href="reference.html#chrono.reference.cpp0x.duration_hpp.duration" title="Class Template duration<>"><code class="computeroutput"><span class="identifier">duration</span></code></a> unit names come in two
- varieties: long and short. The default constructed <a class="link" href="reference.html#chrono.reference.io.chrono_io_hpp.duration_punct" title="Template Class duration_punct<>"><code class="computeroutput"><span class="identifier">duration_punct</span></code></a> provides names
- in the long format. These names are English descriptions. Other languages
- are supported by constructing a <a class="link" href="reference.html#chrono.reference.io.chrono_io_hpp.duration_punct" title="Template Class duration_punct<>"><code class="computeroutput"><span class="identifier">duration_punct</span></code></a> with the proper
- spellings for "hours", "minutes" and "seconds",
- and their abbreviations (for the short format). The short or long format
- can be easily chosen by streaming a <code class="computeroutput"><span class="identifier">duration_short</span><span class="special">()</span></code> or <code class="computeroutput"><span class="identifier">duration_long</span><span class="special">()</span></code> manipulator respectively.
- </p>
+ the format is either
+ </p>
+<pre class="programlisting"><span class="special"><</span><span class="identifier">value</span><span class="special">></span> <span class="special"><</span><span class="identifier">unit</span><span class="special">></span>
+</pre>
<p>
- A <a class="link" href="reference.html#chrono.reference.cpp0x.time_point_hpp.time_point" title="Class template time_point<>"><code class="computeroutput"><span class="identifier">time_point</span></code></a> is formatted by outputting
- its internal <a class="link" href="reference.html#chrono.reference.cpp0x.duration_hpp.duration" title="Class Template duration<>"><code class="computeroutput"><span class="identifier">duration</span></code></a> followed by a string
- that describes the <a class="link" href="reference.html#chrono.reference.cpp0x.time_point_hpp.time_point" title="Class template time_point<>"><code class="computeroutput"><span class="identifier">time_point</span></code></a><code class="computeroutput"><span class="special">::</span><span class="identifier">clock</span></code> epoch. This string will vary for
- each distinct clock, and for each implementation of the supplied clocks.
- </p>
+ or
+ </p>
+<pre class="programlisting"><span class="special"><</span><span class="identifier">unit</span><span class="special">></span> <span class="special"><</span><span class="identifier">value</span><span class="special">></span>
+</pre>
+<div class="warning"><table border="0" summary="Warning">
+<tr>
+<td rowspan="2" align="center" valign="top" width="25"><img alt="[Warning]" src="../../../doc/src/images/warning.png"></td>
+<th align="left">Warning</th>
+</tr>
+<tr><td align="left" valign="top">
+<p>
+ Need to be changed This is followed by a single space and then the
+ compile-time unit name of the <a class="link" href="reference.html#chrono.reference.cpp0x.duration_hpp.duration" title="Class Template duration<>"><code class="computeroutput"><span class="identifier">duration</span></code></a>. This unit name is
+ built on the string returned from <code class="computeroutput"><span class="identifier">ratio_string</span><span class="special"><></span></code> and the data used to construct
+ the <a class="link" href="reference.html#chrono.reference.io_v1.chrono_io_hpp.duration_punct" title="Template Class duration_punct<>"><code class="computeroutput"><span class="identifier">duration_punct</span></code></a> which was inserted
+ into the stream's locale. If a <a class="link" href="reference.html#chrono.reference.io_v1.chrono_io_hpp.duration_punct" title="Template Class duration_punct<>"><code class="computeroutput"><span class="identifier">duration_punct</span></code></a> has not been
+ inserted into the stream's locale, a default constructed <a class="link" href="reference.html#chrono.reference.io_v1.chrono_io_hpp.duration_punct" title="Template Class duration_punct<>"><code class="computeroutput"><span class="identifier">duration_punct</span></code></a> will be added
+ to the stream's locale.
+ </p>
+<p>
+ <a class="link" href="reference.html#chrono.reference.cpp0x.duration_hpp.duration" title="Class Template duration<>"><code class="computeroutput"><span class="identifier">duration</span></code></a> unit names come in
+ two varieties: long(prefix) and short(symbol). The default constructed
+ <a class="link" href="reference.html#chrono.reference.io_v1.chrono_io_hpp.duration_punct" title="Template Class duration_punct<>"><code class="computeroutput"><span class="identifier">duration_punct</span></code></a> provides names
+ in the long(prefix) format. These names are English descriptions. Other
+ languages are supported by constructing a <a class="link" href="reference.html#chrono.reference.io_v1.chrono_io_hpp.duration_punct" title="Template Class duration_punct<>"><code class="computeroutput"><span class="identifier">duration_punct</span></code></a> with the proper
+ spellings for "hours", "minutes" and "seconds",
+ and their abbreviations (for the short format). The short or long format
+ can be easily chosen by streaming a <code class="computeroutput"><span class="identifier">duration_short</span><span class="special">()</span></code> or <code class="computeroutput"><span class="identifier">duration_long</span><span class="special">()</span></code> manipulator respectively or using
+ the parameterized manimulator <code class="computeroutput"><span class="identifier">duration_fmt</span><span class="special">(</span><span class="identifier">duration_style</span><span class="special">::</span><span class="identifier">prefix</span><span class="special">)</span></code> or <code class="computeroutput"><span class="identifier">duration_fmt</span><span class="special">(</span><span class="identifier">duration_style</span><span class="special">::</span><span class="identifier">symbol</span><span class="special">)</span></code>.
+ </p>
+</td></tr>
+</table></div>
<p>
- <span class="bold"><strong>Example:</strong></span>
- </p>
+ <span class="bold"><strong>Example:</strong></span>
+ </p>
<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">iostream</span><span class="special">></span>
<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">chrono</span><span class="special">/</span><span class="identifier">chrono_io</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span>
<span class="keyword">using</span> <span class="keyword">namespace</span> <span class="identifier">std</span><span class="special">;</span>
<span class="keyword">using</span> <span class="keyword">namespace</span> <span class="identifier">boost</span><span class="special">;</span>
+ <span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"milliseconds(1) = "</span>
+ <span class="special"><<</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">milliseconds</span><span class="special">(</span><span class="number">1</span><span class="special">)</span> <span class="special"><<</span> <span class="char">'\n'</span><span class="special">;</span>
+
<span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"milliseconds(3) + microseconds(10) = "</span>
<span class="special"><<</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">milliseconds</span><span class="special">(</span><span class="number">3</span><span class="special">)</span> <span class="special">+</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">microseconds</span><span class="special">(</span><span class="number">10</span><span class="special">)</span> <span class="special"><<</span> <span class="char">'\n'</span><span class="special">;</span>
<span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"ClockTick(3) + boost::chrono::nanoseconds(10) = "</span>
<span class="special"><<</span> <span class="identifier">ClockTick</span><span class="special">(</span><span class="number">3</span><span class="special">)</span> <span class="special">+</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">nanoseconds</span><span class="special">(</span><span class="number">10</span><span class="special">)</span> <span class="special"><<</span> <span class="char">'\n'</span><span class="special">;</span>
- <span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"\nSet cout to use short names:\n"</span><span class="special">;</span>
- <span class="identifier">cout</span> <span class="special"><<</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration_short</span><span class="special">;</span>
-
- <span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"milliseconds(3) + microseconds(10) = "</span>
- <span class="special"><<</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">milliseconds</span><span class="special">(</span><span class="number">3</span><span class="special">)</span> <span class="special">+</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">microseconds</span><span class="special">(</span><span class="number">10</span><span class="special">)</span> <span class="special"><<</span> <span class="char">'\n'</span><span class="special">;</span>
-
- <span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"hours(3) + minutes(10) = "</span>
- <span class="special"><<</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">hours</span><span class="special">(</span><span class="number">3</span><span class="special">)</span> <span class="special">+</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">minutes</span><span class="special">(</span><span class="number">10</span><span class="special">)</span> <span class="special"><<</span> <span class="char">'\n'</span><span class="special">;</span>
-
- <span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"ClockTick(3) + nanoseconds(10) = "</span>
- <span class="special"><<</span> <span class="identifier">ClockTick</span><span class="special">(</span><span class="number">3</span><span class="special">)</span> <span class="special">+</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">nanoseconds</span><span class="special">(</span><span class="number">10</span><span class="special">)</span> <span class="special"><<</span> <span class="char">'\n'</span><span class="special">;</span>
-
- <span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"\nsystem_clock::now() = "</span> <span class="special"><<</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">system_clock</span><span class="special">::</span><span class="identifier">now</span><span class="special">()</span> <span class="special"><<</span> <span class="char">'\n'</span><span class="special">;</span>
-<span class="preprocessor">#ifdef</span> <span class="identifier">BOOST_CHRONO_HAS_CLOCK_STEADY</span>
- <span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"steady_clock::now() = "</span> <span class="special"><<</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">steady_clock</span><span class="special">::</span><span class="identifier">now</span><span class="special">()</span> <span class="special"><<</span> <span class="char">'\n'</span><span class="special">;</span>
-<span class="preprocessor">#endif</span>
- <span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"\nSet cout to use long names:\n"</span>
- <span class="special"><<</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration_long</span>
- <span class="special"><<</span> <span class="string">"high_resolution_clock::now() = "</span>
- <span class="special"><<</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">high_resolution_clock</span><span class="special">::</span><span class="identifier">now</span><span class="special">()</span> <span class="special"><<</span> <span class="char">'\n'</span><span class="special">;</span>
+ <span class="comment">// ...</span>
<span class="keyword">return</span> <span class="number">0</span><span class="special">;</span>
<span class="special">}</span>
</pre>
<p>
- The output could be
- </p>
-<pre class="programlisting"><span class="identifier">milliseconds</span><span class="special">(</span><span class="number">3</span><span class="special">)</span> <span class="special">+</span> <span class="identifier">microseconds</span><span class="special">(</span><span class="number">10</span><span class="special">)</span> <span class="special">=</span> <span class="number">3010</span> <span class="identifier">microseconds</span>
+ The output could be
+ </p>
+<pre class="programlisting"><span class="identifier">milliseconds</span><span class="special">(</span><span class="number">1</span><span class="special">)</span> <span class="special">=</span> <span class="number">1</span> <span class="identifier">microsecond</span>
+<span class="identifier">milliseconds</span><span class="special">(</span><span class="number">3</span><span class="special">)</span> <span class="special">+</span> <span class="identifier">microseconds</span><span class="special">(</span><span class="number">10</span><span class="special">)</span> <span class="special">=</span> <span class="number">3010</span> <span class="identifier">microseconds</span>
<span class="identifier">hours</span><span class="special">(</span><span class="number">3</span><span class="special">)</span> <span class="special">+</span> <span class="identifier">minutes</span><span class="special">(</span><span class="number">10</span><span class="special">)</span> <span class="special">=</span> <span class="number">190</span> <span class="identifier">minutes</span>
<span class="identifier">ClockTick</span><span class="special">(</span><span class="number">3</span><span class="special">)</span> <span class="special">+</span> <span class="identifier">nanoseconds</span><span class="special">(</span><span class="number">10</span><span class="special">)</span> <span class="special">=</span> <span class="number">56</span> <span class="special">[</span><span class="number">1</span><span class="special">/</span><span class="number">5000000000</span><span class="special">]</span><span class="identifier">seconds</span>
<span class="identifier">Set</span> <span class="identifier">cout</span> <span class="identifier">to</span> <span class="identifier">use</span> <span class="keyword">short</span> <span class="identifier">names</span><span class="special">:</span>
-<span class="identifier">milliseconds</span><span class="special">(</span><span class="number">3</span><span class="special">)</span> <span class="special">+</span> <span class="identifier">microseconds</span><span class="special">(</span><span class="number">10</span><span class="special">)</span> <span class="special">=</span> <span class="number">3010</span> <span class="special">[</span><span class="identifier">mu</span><span class="special">]</span><span class="identifier">s</span>
+<span class="identifier">milliseconds</span><span class="special">(</span><span class="number">3</span><span class="special">)</span> <span class="special">+</span> <span class="identifier">microseconds</span><span class="special">(</span><span class="number">10</span><span class="special">)</span> <span class="special">=</span> <span class="number">3010</span> μs
<span class="identifier">hours</span><span class="special">(</span><span class="number">3</span><span class="special">)</span> <span class="special">+</span> <span class="identifier">minutes</span><span class="special">(</span><span class="number">10</span><span class="special">)</span> <span class="special">=</span> <span class="number">190</span> <span class="identifier">m</span>
<span class="identifier">ClockTick</span><span class="special">(</span><span class="number">3</span><span class="special">)</span> <span class="special">+</span> <span class="identifier">nanoseconds</span><span class="special">(</span><span class="number">10</span><span class="special">)</span> <span class="special">=</span> <span class="number">56</span> <span class="special">[</span><span class="number">1</span><span class="special">/</span><span class="number">5000000000</span><span class="special">]</span><span class="identifier">s</span>
<span class="identifier">high_resolution_clock</span><span class="special">::</span><span class="identifier">now</span><span class="special">()</span> <span class="special">=</span> <span class="number">37297387655134</span> <span class="identifier">nanoseconds</span> <span class="identifier">since</span> <span class="identifier">boot</span>
</pre>
<p>
- Parsing a <a class="link" href="reference.html#chrono.reference.cpp0x.duration_hpp.duration" title="Class Template duration<>"><code class="computeroutput"><span class="identifier">duration</span></code></a> follows rules analogous
- to the <a class="link" href="reference.html#chrono.reference.cpp0x.duration_hpp.duration" title="Class Template duration<>"><code class="computeroutput"><span class="identifier">duration</span></code></a> converting constructor.
- A value and a unit (short or long) are read from the <code class="computeroutput"><span class="identifier">basic_istream</span></code>.
- If the <a class="link" href="reference.html#chrono.reference.cpp0x.duration_hpp.duration" title="Class Template duration<>"><code class="computeroutput"><span class="identifier">duration</span></code></a> has an integral representation,
- then the value parsed must be exactly representable in the target <a class="link" href="reference.html#chrono.reference.cpp0x.duration_hpp.duration" title="Class Template duration<>"><code class="computeroutput"><span class="identifier">duration</span></code></a>
- (after conversion to the target <a class="link" href="reference.html#chrono.reference.cpp0x.duration_hpp.duration" title="Class Template duration<>"><code class="computeroutput"><span class="identifier">duration</span></code></a> units), else <code class="computeroutput"><span class="identifier">failbit</span></code> is set. <a class="link" href="reference.html#chrono.reference.cpp0x.duration_hpp.duration" title="Class Template duration<>"><code class="computeroutput"><span class="identifier">duration</span></code></a>s based on floating-point
- representations can be parsed using any units that do not cause overflow.
- </p>
+ As can be seen, each duration type can be streamed without having to
+ manually stream the compile-time units after the run-time value. And
+ when the compile-time unit is known to be a "common unit",
+ English names are used. For "uncommon units" a unit name is
+ composed from the reduced numerator and denominator of the associated
+ <code class="computeroutput"><span class="identifier">ratio</span></code>. Whatever stream/locale
+ settings are set for <code class="computeroutput"><span class="identifier">duration</span><span class="special">::</span><span class="identifier">rep</span></code>
+ are used for the value. Additionally, when the value is 1, singular forms
+ for the units are used.
+ </p>
<p>
- For example a stream containing "5000 milliseconds" can be parsed
- into seconds, but if the stream contains "5001 milliseconds",
- parsing into <code class="computeroutput"><span class="identifier">seconds</span></code> will
- cause <code class="computeroutput"><span class="identifier">failbit</span></code> to be set.
- </p>
+ Sometimes it is desired to shorten these names by using the SI symbols
+ instead of SI prefixes. This can be accomplished with the use of the
+ <a class="link" href="reference.html#chrono.reference.io.duration_io_hpp.manipulators.symbol_format" title="Non Member Function symbol_format(ios_base&)"><code class="computeroutput"><span class="identifier">symbol_format</span></code></a> manipulator <a href="#ftn.chrono.users_guide.tutorial.i_o.duration_io.f0" class="footnote" name="chrono.users_guide.tutorial.i_o.duration_io.f0"><sup class="footnote">[1]</sup></a>:
+ </p>
+<pre class="programlisting"><span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"\nSet cout to use short names:\n"</span><span class="special">;</span>
+<span class="identifier">cout</span> <span class="special"><<</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">symbol_format</span><span class="special">;</span>
+
+<span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"milliseconds(3) + microseconds(10) = "</span>
+ <span class="special"><<</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">milliseconds</span><span class="special">(</span><span class="number">3</span><span class="special">)</span> <span class="special">+</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">microseconds</span><span class="special">(</span><span class="number">10</span><span class="special">)</span> <span class="special"><<</span> <span class="char">'\n'</span><span class="special">;</span>
+
+<span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"hours(3) + minutes(10) = "</span>
+ <span class="special"><<</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">hours</span><span class="special">(</span><span class="number">3</span><span class="special">)</span> <span class="special">+</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">minutes</span><span class="special">(</span><span class="number">10</span><span class="special">)</span> <span class="special"><<</span> <span class="char">'\n'</span><span class="special">;</span>
+
+<span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"ClockTick(3) + nanoseconds(10) = "</span>
+ <span class="special"><<</span> <span class="identifier">ClockTick</span><span class="special">(</span><span class="number">3</span><span class="special">)</span> <span class="special">+</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">nanoseconds</span><span class="special">(</span><span class="number">10</span><span class="special">)</span> <span class="special"><<</span> <span class="char">'\n'</span><span class="special">;</span>
+</pre>
<p>
- <span class="bold"><strong>Example:</strong></span>
- </p>
+ The output could be
+ </p>
+<pre class="programlisting"><span class="identifier">Set</span> <span class="identifier">cout</span> <span class="identifier">to</span> <span class="identifier">use</span> <span class="keyword">short</span> <span class="identifier">names</span><span class="special">:</span>
+<span class="identifier">milliseconds</span><span class="special">(</span><span class="number">3</span><span class="special">)</span> <span class="special">+</span> <span class="identifier">microseconds</span><span class="special">(</span><span class="number">10</span><span class="special">)</span> <span class="special">=</span> <span class="number">3010</span> μs
+<span class="identifier">hours</span><span class="special">(</span><span class="number">3</span><span class="special">)</span> <span class="special">+</span> <span class="identifier">minutes</span><span class="special">(</span><span class="number">10</span><span class="special">)</span> <span class="special">=</span> <span class="number">190</span> <span class="identifier">m</span>
+<span class="identifier">ClockTick</span><span class="special">(</span><span class="number">3</span><span class="special">)</span> <span class="special">+</span> <span class="identifier">nanoseconds</span><span class="special">(</span><span class="number">10</span><span class="special">)</span> <span class="special">=</span> <span class="number">56</span> <span class="special">[</span><span class="number">1</span><span class="special">/</span><span class="number">5000000000</span><span class="special">]</span><span class="identifier">s</span>
+
+<span class="identifier">system_clock</span><span class="special">::</span><span class="identifier">now</span><span class="special">()</span> <span class="special">=</span> <span class="number">129387415616250000</span> <span class="special">[</span><span class="number">1</span><span class="special">/</span><span class="number">10000000</span><span class="special">]</span><span class="identifier">s</span> <span class="identifier">since</span> <span class="identifier">Jan</span> <span class="number">1</span><span class="special">,</span> <span class="number">1970</span>
+<span class="identifier">monotonic_clock</span><span class="special">::</span><span class="identifier">now</span><span class="special">()</span> <span class="special">=</span> <span class="number">37297387636417</span> <span class="identifier">ns</span> <span class="identifier">since</span> <span class="identifier">boot</span>
+
+<span class="identifier">Set</span> <span class="identifier">cout</span> <span class="identifier">to</span> <span class="identifier">use</span> <span class="keyword">long</span> <span class="identifier">names</span><span class="special">:</span>
+<span class="identifier">high_resolution_clock</span><span class="special">::</span><span class="identifier">now</span><span class="special">()</span> <span class="special">=</span> <span class="number">37297387655134</span> <span class="identifier">nanoseconds</span> <span class="identifier">since</span> <span class="identifier">boot</span>
+</pre>
+<p>
+ The μ for microsecond is specified to be U+00B5, encoded as UTF-8, UTF-16
+ or UTF-32 as appropriate for the stream's character size.
+ </p>
+<p>
+ When the format decision is taken at runtime, it could be better to use
+ the parameterized manipulator <a class="link" href="reference.html#chrono.reference.io.duration_io_hpp.manipulators.duration_fmt" title="Template Class duration_fmt"><code class="computeroutput"><span class="identifier">duration_fmt</span></code></a> as in
+ </p>
+<pre class="programlisting"><span class="identifier">duration_style</span> <span class="identifier">style</span><span class="special">;</span>
+<span class="comment">//...</span>
+<span class="identifier">cout</span> <span class="special"><<</span> <span class="identifier">duration_fmt</span><span class="special">(</span><span class="identifier">style</span><span class="special">);</span>
+</pre>
+<p>
+ Parsing a <a class="link" href="reference.html#chrono.reference.cpp0x.duration_hpp.duration" title="Class Template duration<>"><code class="computeroutput"><span class="identifier">duration</span></code></a> follows rules analogous
+ to the <a class="link" href="reference.html#chrono.reference.cpp0x.duration_hpp.duration" title="Class Template duration<>"><code class="computeroutput"><span class="identifier">duration</span></code></a> converting constructor.
+ A value and a unit (SI symbol or prefixed) are read from the <code class="computeroutput"><span class="identifier">basic_istream</span></code>. If the <a class="link" href="reference.html#chrono.reference.cpp0x.duration_hpp.duration" title="Class Template duration<>"><code class="computeroutput"><span class="identifier">duration</span></code></a> has an integral representation,
+ then the value parsed must be exactly representable in the target <a class="link" href="reference.html#chrono.reference.cpp0x.duration_hpp.duration" title="Class Template duration<>"><code class="computeroutput"><span class="identifier">duration</span></code></a> (after conversion to
+ the target <a class="link" href="reference.html#chrono.reference.cpp0x.duration_hpp.duration" title="Class Template duration<>"><code class="computeroutput"><span class="identifier">duration</span></code></a> units), else <code class="computeroutput"><span class="identifier">failbit</span></code> is set. <a class="link" href="reference.html#chrono.reference.cpp0x.duration_hpp.duration" title="Class Template duration<>"><code class="computeroutput"><span class="identifier">duration</span></code></a>s based on floating-point
+ representations can be parsed using any units that do not cause overflow.
+ </p>
+<p>
+ For example a stream containing "5000 milliseconds" can be
+ parsed into seconds, but if the stream contains "3001 ms",
+ parsing into <code class="computeroutput"><span class="identifier">seconds</span></code>
+ will cause <code class="computeroutput"><span class="identifier">failbit</span></code> to
+ be set.
+ </p>
+<p>
+ <span class="bold"><strong>Example:</strong></span>
+ </p>
<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">chrono</span><span class="special">/</span><span class="identifier">chrono_io</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span>
<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">sstream</span><span class="special">></span>
<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">cassert</span><span class="special">></span>
<span class="special">}</span>
</pre>
<p>
- Note that a <a class="link" href="reference.html#chrono.reference.cpp0x.duration_hpp.duration" title="Class Template duration<>"><code class="computeroutput"><span class="identifier">duration</span></code></a> failure may occur late
- in the parsing process. This means that the characters making up the failed
- parse in the stream are usually consumed despite the failure to successfully
- parse.
- </p>
+
Note that a <a class="link" href="reference.html#chrono.reference.cpp0x.duration_hpp.duration" title="Class Template duration<>"><code class="computeroutput"><span class="identifier">duration</span></code></a> failure may occur late
+ in the parsing process. This means that the characters making up the
+ failed parse in the stream are usually consumed despite the failure to
+ successfully parse.
+ </p>
<p>
- Parsing a <a class="link" href="reference.html#chrono.reference.cpp0x.time_point_hpp.time_point" title="Class template time_point<>"><code class="computeroutput"><span class="identifier">time_point</span></code></a> involves first parsing
- a <a class="link" href="reference.html#chrono.reference.cpp0x.duration_hpp.duration" title="Class Template duration<>"><code class="computeroutput"><span class="identifier">duration</span></code></a> and then parsing the
- epoch string. If the epoch string does not match that associated with
- <code class="computeroutput"><span class="identifier">time_point</span><span class="special">::</span><span class="identifier">clock</span></code> then failbit will be set.
- </p>
+ Sometimes in templated code it is difficult to know what the unit of
+ your duration is. It is all deterministic, and inspect-able. But it can
+ be inconvenient to do so, especially if you just need to print out a
+ "debugging" statement. For example:
+ </p>
+<pre class="programlisting"><span class="comment">// round to nearest, to even on tie</span>
+<span class="keyword">template</span> <span class="special"><</span><span class="keyword">class</span> <a class="link" href="reference.html#chrono.reference.cpp0x.duration_hpp.duration" title="Class Template duration<>"><code class="computeroutput"><span class="identifier">To</span></code></a><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Rep</span><span class="special">,</span> <span class="keyword">class</span> <span class="identifier">Period</span><span class="special">></span>
+<span class="identifier">To</span>
+<span class="identifier">round</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">duration</span><span class="special"><</span><span class="identifier">Rep</span><span class="special">,</span> <span class="identifier">Period</span><span class="special">>&</span> <span class="identifier">d</span><span class="special">)</span>
+<span class="special">{</span>
+ <span class="identifier">To</span> <span class="identifier">t0</span> <span class="special">=</span> <span class="identifier">duration_cast</span><span class="special"><</span><span class="identifier">To</span><span class="special">>(</span><span class="identifier">d</span><span class="special">);</span>
+ <span class="identifier">To</span> <span class="identifier">t1</span> <span class="special">=</span> <span class="identifier">t0</span><span class="special">;</span>
+ <span class="special">++</span><span class="identifier">t1</span><span class="special">;</span>
+ <span class="keyword">auto</span> <span class="identifier">diff0</span> <span class="special">=</span> <span class="identifier">d</span> <span class="special">-</span> <span class="identifier">t0</span><span class="special">;</span>
+ <span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"diff0 = "</span> <span class="special"><<</span> <span class="identifier">diff0</span> <span class="special"><<</span> <span class="char">'\n'</span><span class="special">;</span>
+ <span class="keyword">auto</span> <span class="identifier">diff1</span> <span class="special">=</span> <span class="identifier">t1</span> <span class="special">-</span> <span class="identifier">d</span><span class="special">;</span>
+ <span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"diff1 = "</span> <span class="special"><<</span> <span class="identifier">diff1</span> <span class="special"><<</span> <span class="char">'\n'</span><span class="special">;</span>
+ <span class="keyword">if</span> <span class="special">(</span><span class="identifier">diff0</span> <span class="special">==</span> <span class="identifier">diff1</span><span class="special">)</span>
+ <span class="special">{</span>
+ <span class="keyword">if</span> <span class="special">(</span><span class="identifier">t0</span><span class="special">.</span><span class="identifier">count</span><span class="special">()</span> <span class="special">&</span> <span class="number">1</span><span class="special">)</span>
+ <span class="keyword">return</span> <span class="identifier">t1</span><span class="special">;</span>
+ <span class="keyword">return</span> <span class="identifier">t0</span><span class="special">;</span>
+ <span class="special">}</span>
+ <span class="keyword">else</span> <span class="keyword">if</span> <span class="special">(</span><span class="identifier">diff0</span> <span class="special"><</span> <span class="identifier">diff1</span><span class="special">)</span>
+ <span class="keyword">return</span> <span class="identifier">t0</span><span class="special">;</span>
+ <span class="keyword">return</span> <span class="identifier">t1</span><span class="special">;</span>
+<span class="special">}</span>
+</pre>
<p>
- <span class="bold"><strong>Example:</strong></span>
- </p>
+ This is where I/O for duration really shines. The compiler knows what
+ the type of diff0 is and with this proposal that type (with proper units)
+ will automatically be printed out for you. For example:
+ </p>
+<pre class="programlisting"><span class="identifier">milliseconds</span> <span class="identifier">ms</span> <span class="special">=</span> <span class="identifier">round</span><span class="special"><</span><span class="identifier">milliseconds</span><span class="special">>(</span><span class="identifier">nanoseconds</span><span class="special">(</span><span class="number">123</span><span class="special">));</span> <span class="comment">// diff0 = 123 nanoseconds</span>
+ <span class="comment">// diff1 = 999877 nanoseconds</span>
+<span class="identifier">milliseconds</span> <span class="identifier">ms</span> <span class="special">=</span> <span class="identifier">round</span><span class="special"><</span><span class="identifier">milliseconds</span><span class="special">>(</span><span class="identifier">Ticks</span><span class="special">(</span><span class="number">44</span><span class="special">));</span> <span class="comment">// diff0 = 2 [1/3000]seconds</span>
+ <span class="comment">// diff1 = 1 [1/3000]second</span>
+</pre>
+<p>
+ This simple I/O will make duration so much more accessible to programmers.
+ </p>
+</div>
+<div class="section">
+<div class="titlepage"><div><div><h5 class="title">
+<a name="chrono.users_guide.tutorial.i_o.system_clock_time_point_io"></a><a class="link" href="users_guide.html#chrono.users_guide.tutorial.i_o.system_clock_time_point_io" title="system_clock::time_point"><code class="computeroutput"><span class="identifier">system_clock</span><span class="special">::</span><span class="identifier">time_point</span></code></a>
+</h5></div></div></div>
+<p>
+ <a class="link" href="reference.html#chrono.reference.cpp0x.system_clocks_hpp.system_clock" title="Class system_clock"><code class="computeroutput"><span class="identifier">system_clock</span></code></a> is special. It
+ is the only clock that has conversions between its <code class="computeroutput"><span class="identifier">time_point</span></code>
+ and <code class="computeroutput"><span class="identifier">time_t</span></code>. C subsequently
+ relates time_t to the <a href="http://en.wikipedia.org/wiki/Gregorian_calendar" target="_top">Gregorian
+ calendar</a> via <code class="computeroutput"><span class="identifier">ctime</span></code>,
+ <code class="computeroutput"><span class="identifier">gmtime</span></code>, <code class="computeroutput"><span class="identifier">localtime</span></code>, and <code class="computeroutput"><span class="identifier">strftime</span></code>.
+ Neither C, nor POSIX relate <code class="computeroutput"><span class="identifier">time_t</span></code>
+ to any calendar other than the <a href="http://en.wikipedia.org/wiki/Gregorian_calendar" target="_top">Gregorian
+ calendar</a>. ISO 8601 is specified only in terms of the <a href="http://en.wikipedia.org/wiki/Gregorian_calendar" target="_top">Gregorian
+ calendar</a>.
+ </p>
+<p>
+ <span class="bold"><strong>Boost.Chrono</strong></span> provides <code class="computeroutput"><span class="identifier">system_clock</span><span class="special">::</span><span class="identifier">time_point</span></code> I/O in terms of the Gregorian
+ calendar, and no other calendar. However as <code class="computeroutput"><span class="identifier">system_clock</span><span class="special">::</span><span class="identifier">time_point</span></code>
+ remains convertible with <code class="computeroutput"><span class="identifier">time_t</span></code>,
+ it is possible for clients to create other calendars which interoperate
+ with <code class="computeroutput"><span class="identifier">time_t</span></code> and subsequently
+ <code class="computeroutput"><span class="identifier">system_clock</span><span class="special">::</span><span class="identifier">time_point</span></code>.
+ </p>
+<p>
+ Furthermore, it is existing practice for all major hosted operating systems
+ to store system time in a format which facilitates display as <a href="http://en.wikipedia.org/wiki/Coordinated_Universal_Time" target="_top">Coordinated
+ Universal Time</a> (UTC). Therefore <span class="bold"><strong>Boost.Chrono</strong></span>
+ provides that the default output for <code class="computeroutput"><span class="identifier">system_clock</span><span class="special">::</span><span class="identifier">time_point</span></code>
+ be in a format that represents a point in time with respect to UTC.
+ </p>
+<pre class="programlisting"><span class="identifier">cout</span> <span class="special"><<</span> <span class="identifier">system_clock</span><span class="special">::</span><span class="identifier">now</span><span class="special">()</span> <span class="special"><<</span> <span class="char">'\n'</span><span class="special">;</span>
+</pre>
+<p>
+ could output
+ </p>
+<pre class="programlisting"><span class="number">2011</span><span class="special">-</span><span class="number">09</span><span class="special">-</span><span class="number">15</span> <span class="number">18</span><span class="special">:</span><span class="number">36</span><span class="special">:</span><span class="number">59.325132</span> <span class="special">+</span><span class="number">0000</span>
+</pre>
+<p>
+ This format is strongly influenced by ISO 8601, but places a ' ' between
+ the date and time instead of a 'T'. The former appears to more accurately
+ represent existing practice. A fully numeric format was chosen so as
+ to be understandable to as large a group of human readers as possible.
+ A 24 hour format was chosen for the same reasons.
+ </p>
+<p>
+ Of the referenced standards, only ISO 8601 discusses the output of fractional
+ seconds. Neither C nor POSIX have built-in functionality for this. However
+ it appears to be universal (as of this writing) that <code class="computeroutput"><span class="identifier">system_clock</span><span class="special">::</span><span class="identifier">period</span></code>
+ is sub-second. And it seems desirable that if you stream out a <code class="computeroutput"><span class="identifier">system_clock</span><span class="special">::</span><span class="identifier">time_point</span></code>, you ought to be able to
+ stream it back in and get the same value. Therefore the streaming of
+ fractional seconds (at least by default) appears to be unavoidable.
+ </p>
+<p>
+ Finally the trailing " +0000" disambiguates the UTC-formatted
+ <code class="computeroutput"><span class="identifier">system_clock</span><span class="special">::</span><span class="identifier">time_point</span></code> from one formatted with
+ respect to the local time zone of the computer. The latter can easily
+ be achieved with:
+ </p>
+<pre class="programlisting"><span class="identifier">cout</span> <span class="special"><<</span> <span class="identifier">time_fmt</span><span class="special">(</span><span class="identifier">local</span><span class="special">)</span> <span class="special"><<</span> <span class="identifier">system_clock</span><span class="special">::</span><span class="identifier">now</span><span class="special">()</span> <span class="special"><<</span> <span class="char">'\n'</span><span class="special">;</span>
+</pre>
+<p>
+ that could result in
+ </p>
+<pre class="programlisting"><span class="number">2011</span><span class="special">-</span><span class="number">09</span><span class="special">-</span><span class="number">15</span> <span class="number">14</span><span class="special">:</span><span class="number">36</span><span class="special">:</span><span class="number">59.325132</span> <span class="special">-</span><span class="number">0400</span>
+</pre>
+<p>
+ Note that <code class="computeroutput"><span class="identifier">system_clock</span><span class="special">::</span><span class="identifier">time_point</span></code>
+ itself is neither UTC, nor the local time. However in practice, <code class="computeroutput"><span class="identifier">system_clock</span><span class="special">::</span><span class="identifier">time_point</span></code> is a count of ticks beyond
+ some epoch which is synchronized with UTC. So as a mobile computer moves
+ across time zones, the time zone traversal does not impact the value
+ of a <code class="computeroutput"><span class="identifier">system_clock</span><span class="special">::</span><span class="identifier">time_point</span></code> produced by <code class="computeroutput"><span class="identifier">system_clock</span><span class="special">::</span><span class="identifier">now</span><span class="special">()</span></code>.
+ And it is only in formatting it for human consumption that one can choose
+ UTC or the local time zone. C and POSIX treat <code class="computeroutput"><span class="identifier">time_t</span></code>
+ just as <span class="bold"><strong>Boost.Chrono</strong></span> treats <code class="computeroutput"><span class="identifier">system_clock</span><span class="special">::</span><span class="identifier">time_point</span></code>:
+ </p>
+<pre class="programlisting"><span class="identifier">tm</span><span class="special">*</span> <span class="identifier">gmtime</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">time_t</span><span class="special">*</span> <span class="identifier">timer</span><span class="special">)</span> <span class="special">-></span> <span class="identifier">UTC</span>
+<span class="identifier">tm</span><span class="special">*</span> <span class="identifier">localtime</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">time_t</span><span class="special">*</span> <span class="identifier">timer</span><span class="special">)</span> <span class="special">-></span> <span class="identifier">local</span> <span class="identifier">time</span>
+</pre>
+<p>
+ This proposal simply extends the C/POSIX <code class="computeroutput"><span class="identifier">time_t</span></code>
+ functionality to C++ syntax and <code class="computeroutput"><span class="identifier">system_clock</span><span class="special">::</span><span class="identifier">time_point</span></code>.
+ </p>
+<p>
+ The <code class="computeroutput"><span class="identifier">time_fmt</span><span class="special">()</span></code>
+ manipulator is "sticky". It will remain in effect until the
+ stream destructs or until it is changed. The stream can be reset to its
+ default state with:
+ </p>
+<pre class="programlisting"><span class="identifier">cout</span> <span class="special"><<</span> <span class="identifier">time_fmt</span><span class="special">(</span><span class="identifier">utc</span><span class="special">);</span>
+</pre>
+<p>
+ And the formatting can be further customized by using the time format
+ sequences. For example:
+ </p>
+<pre class="programlisting"><span class="identifier">cout</span> <span class="special"><<</span> <span class="identifier">time_fmt</span><span class="special">(</span><span class="identifier">local</span><span class="special">,</span> <span class="string">"%A %B %e, %Y %r"</span><span class="special">);</span>
+<span class="identifier">cout</span> <span class="special"><<</span> <span class="identifier">system_clock</span><span class="special">::</span><span class="identifier">now</span><span class="special">()</span> <span class="special"><<</span> <span class="char">'\n'</span><span class="special">;</span> <span class="comment">// Sunday April 24, 2011 02:36:59 PM</span>
+</pre>
+<p>
+ When specifying formatting manipulators for wide streams, use wide strings.
+ </p>
+<p>
+ You can use the same manipulators with istreams to specify parsing sequences.
+ </p>
+<p>
+ Unfortunately there are no formatting/parsing sequences which indicate
+ fractional seconds. <span class="bold"><strong>Boost.Chrono</strong></span> does
+ not provide such sequences. In the meantime, one can format and parse
+ fractional seconds for <code class="computeroutput"><span class="identifier">system_clock</span><span class="special">::</span><span class="identifier">time_point</span></code>
+ by defaulting the format, or by using an empty string in <code class="computeroutput"><span class="identifier">time_fmt</span><span class="special">()</span></code>.
+ </p>
+<p>
+ The stream's current locale may impact the parsing/format sequences supplied
+ to the <code class="computeroutput"><span class="identifier">system_clock</span><span class="special">::</span><span class="identifier">time_point</span></code> manipulators (e.g. names
+ of days of the week, and names of months).
+ </p>
+</div>
+<div class="section">
+<div class="titlepage"><div><div><h5 class="title">
+<a name="chrono.users_guide.tutorial.i_o.other_clocks_time_point_io"></a><a class="link" href="users_guide.html#chrono.users_guide.tutorial.i_o.other_clocks_time_point_io" title="Other clocks time_point">Other
+ clocks time_point</a>
+</h5></div></div></div>
+<p>
+ Unlike <code class="computeroutput"><span class="identifier">system_clock</span><span class="special">::</span><span class="identifier">time_point</span></code>, the other clocks have no
+ conversion with <code class="computeroutput"><span class="identifier">time_t</span></code>.
+ There is likely no relationship between steady_clock::time_point and
+ UTC at all (UTC is not steady).
+ </p>
+<p>
+ In general a <a class="link" href="reference.html#chrono.reference.cpp0x.time_point_hpp.time_point" title="Class template time_point<>"><code class="computeroutput"><span class="identifier">time_point</span></code></a> is formatted by outputting
+ its internal <a class="link" href="reference.html#chrono.reference.cpp0x.duration_hpp.duration" title="Class Template duration<>"><code class="computeroutput"><span class="identifier">duration</span></code></a> followed by a string
+ that describes the <a class="link" href="reference.html#chrono.reference.cpp0x.time_point_hpp.time_point" title="Class template time_point<>"><code class="computeroutput"><span class="identifier">time_point</span></code></a><code class="computeroutput"><span class="special">::</span><span class="identifier">clock</span></code> epoch. This string will vary
+ for each distinct clock, and for each implementation of the supplied
+ clocks.
+ </p>
+<pre class="programlisting"><span class="preprocessor">#ifdef</span> <span class="identifier">BOOST_CHRONO_HAS_CLOCK_STEADY</span>
+ <span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"steady_clock::now() = "</span> <span class="special"><<</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">steady_clock</span><span class="special">::</span><span class="identifier">now</span><span class="special">()</span> <span class="special"><<</span> <span class="char">'\n'</span><span class="special">;</span>
+<span class="preprocessor">#endif</span>
+ <span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"\nSet cout to use long names:\n"</span>
+ <span class="special"><<</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">duration_long</span>
+ <span class="special"><<</span> <span class="string">"high_resolution_clock::now() = "</span>
+ <span class="special"><<</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">chrono</span><span class="special">::</span><span class="identifier">high_resolution_clock</span><span class="special">::</span><span class="identifier">now</span><span class="special">()</span> <span class="special"><<</span> <span class="char">'\n'</span><span class="special">;</span>
+</pre>
+<p>
+ The output could be
+ </p>
+<pre class="programlisting"><span class="identifier">steady_clock</span><span class="special">::</span><span class="identifier">now</span><span class="special">()</span> <span class="special">=</span> <span class="number">37297387636417</span> <span class="identifier">ns</span> <span class="identifier">since</span> <span class="identifier">boot</span>
+
+<span class="identifier">Set</span> <span class="identifier">cout</span> <span class="identifier">to</span> <span class="identifier">use</span> <span class="keyword">long</span> <span class="identifier">names</span><span class="special">:</span>
+<span class="identifier">high_resolution_clock</span><span class="special">::</span><span class="identifier">now</span><span class="special">()</span> <span class="special">=</span> <span class="number">37297387655134</span> <span class="identifier">nanoseconds</span> <span class="identifier">since</span> <span class="identifier">boot</span>
+</pre>
+<p>
+ Parsing a <a class="link" href="reference.html#chrono.reference.cpp0x.time_point_hpp.time_point" title="Class template time_point<>"><code class="computeroutput"><span class="identifier">time_point</span></code></a> involves first parsing
+ a <a class="link" href="reference.html#chrono.reference.cpp0x.duration_hpp.duration" title="Class Template duration<>"><code class="computeroutput"><span class="identifier">duration</span></code></a> and then parsing the
+ epoch string. If the epoch string does not match that associated with
+ <code class="computeroutput"><span class="identifier">time_point</span><span class="special">::</span><span class="identifier">clock</span></code> then failbit will be set.
+ </p>
+<p>
+ <span class="bold"><strong>Example:</strong></span>
+ </p>
<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">chrono</span><span class="special">/</span><span class="identifier">chrono_io</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span>
<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">sstream</span><span class="special">></span>
<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">iostream</span><span class="special">></span>
<span class="special">}</span>
</pre>
<p>
- The output could be:
- </p>
+ The output could be:
+ </p>
<pre class="programlisting"><span class="number">50908679121461</span> <span class="identifier">nanoseconds</span> <span class="identifier">since</span> <span class="identifier">boot</span>
<span class="identifier">That</span> <span class="identifier">took</span> <span class="number">649630</span> <span class="identifier">nanoseconds</span>
</pre>
<p>
- Here's a simple example to find out how many hours the computer has been
- up (on this platform):
- </p>
+ Here's a simple example to find out how many hours the computer has been
+ up (on this platform):
+ </p>
<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">chrono</span><span class="special">/</span><span class="identifier">chrono_io</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span>
<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">iostream</span><span class="special">></span>
<span class="special">}</span>
</pre>
<p>
- The output could be:
- </p>
+ The output could be:
+ </p>
<pre class="programlisting"><span class="number">17.8666</span> <span class="identifier">hours</span> <span class="identifier">since</span> <span class="identifier">boot</span>
</pre>
</div>
+<div class="section">
+<div class="titlepage"><div><div><h5 class="title">
+<a name="chrono.users_guide.tutorial.i_o.low_level_i_o"></a><a class="link" href="users_guide.html#chrono.users_guide.tutorial.i_o.low_level_i_o" title="Low level I/O">Low
+ level I/O</a>
+</h5></div></div></div>
+<p>
+ The I/O interface described in the preceding I/O sections were at the
+ user level. These services are based on low level services that are useful
+ when writing libraries. The low level services are related to access
+ to the associated ios state and locale facets. The design follows the
+ C++ IOStreams standard design:
+ </p>
+<p>
+ The library encapsulate the locale-dependent parsing and formatting of
+ <a class="link" href="reference.html#chrono.reference.cpp0x.duration_hpp.duration" title="Class Template duration<>"><code class="computeroutput"><span class="identifier">duration</span></code></a> into a new facet class.
+ Let's focus on formatting in this example. The concerned facet class
+ is <a class="link" href="reference.html#chrono.reference.io.duration_put_hpp.duration_put" title="Template Class duration_put"><code class="computeroutput"><span class="identifier">duration_put</span></code></a>, analogous to time_put,
+ money_put, etc.
+ </p>
+<p>
+ The use of this facet is similar to the time_put facet.
+ </p>
+</div>
+</div>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="chrono.users_guide.examples"></a><a class="link" href="users_guide.html#chrono.users_guide.examples" title="Examples">Examples</a>
</h3></div></div></div>
-<div class="toc"><dl>
+<div class="toc"><dl class="toc">
<dt><span class="section"><a href="users_guide.html#chrono.users_guide.examples.duration">Duration</a></span></dt>
<dt><span class="section"><a href="users_guide.html#chrono.users_guide.examples.clocks">Clocks</a></span></dt>
<dt><span class="section"><a href="users_guide.html#chrono.users_guide.examples.time_point">Time Point</a></span></dt>
<div class="titlepage"><div><div><h4 class="title">
<a name="chrono.users_guide.examples.duration"></a><a class="link" href="users_guide.html#chrono.users_guide.examples.duration" title="Duration">Duration</a>
</h4></div></div></div>
-<div class="toc"><dl>
+<div class="toc"><dl class="toc">
<dt><span class="section"><a href="users_guide.html#chrono.users_guide.examples.duration.how_you_override_the_duration_s_default_constructor">How
you Override the Duration's Default Constructor</a></span></dt>
<dt><span class="section"><a href="users_guide.html#chrono.users_guide.examples.duration.saturating">Saturating</a></span></dt>
<div class="titlepage"><div><div><h4 class="title">
<a name="chrono.users_guide.examples.clocks"></a><a class="link" href="users_guide.html#chrono.users_guide.examples.clocks" title="Clocks">Clocks</a>
</h4></div></div></div>
-<div class="toc"><dl>
+<div class="toc"><dl class="toc">
<dt><span class="section"><a href="users_guide.html#chrono.users_guide.examples.clocks.cycle_count">Cycle
count</a></span></dt>
<dt><span class="section"><a href="users_guide.html#chrono.users_guide.examples.clocks.xtime_clock">xtime_clock</a></span></dt>
<div class="titlepage"><div><div><h4 class="title">
<a name="chrono.users_guide.examples.time_point"></a><a class="link" href="users_guide.html#chrono.users_guide.examples.time_point" title="Time Point">Time Point</a>
</h4></div></div></div>
-<div class="toc"><dl>
+<div class="toc"><dl class="toc">
<dt><span class="section"><a href="users_guide.html#chrono.users_guide.examples.time_point.min_utility">min
Utility</a></span></dt>
<dt><span class="section"><a href="users_guide.html#chrono.users_guide.examples.time_point.a_tiny_program_that_times_how_long_until_a_key_is_struck">A
<p>
Where:
</p>
-<div class="itemizedlist"><ul class="itemizedlist" type="disc">
+<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<code class="computeroutput"><span class="identifier">d</span></code> is the number of
<code class="computeroutput"><span class="identifier">days</span></code>
Thread Interface Demonstration Program</a>
</h5></div></div></div>
<p>
- The C++0x standard library's multi-threading library requires the ability
+ The C++11 standard library's multi-threading library requires the ability
to deal with the representation of time in a manner consistent with modern
C++ practices. Next is a simulation of this interface.
</p>
<div class="titlepage"><div><div><h4 class="title">
<a name="chrono.users_guide.examples.io"></a><a class="link" href="users_guide.html#chrono.users_guide.examples.io" title="IO">IO</a>
</h4></div></div></div>
-<div class="toc"><dl><dt><span class="section"><a href="users_guide.html#chrono.users_guide.examples.io.french">French Output</a></span></dt></dl></div>
+<div class="toc"><dl
class="toc"><dt><span class="section"><a href="users_guide.html#chrono.users_guide.examples.io.french">French Output</a></span></dt></dl></div>
<div class="section">
<div class="titlepage"><div><div><h5 class="title">
<a name="chrono.users_guide.examples.io.french"></a><a class="link" href="users_guide.html#chrono.users_guide.examples.io.french" title="French Output">French Output</a>
</h3></div></div></div>
<div class="variablelist">
<p class="title"><b></b></p>
-<dl>
+<dl class="variablelist">
<dt><span class="term"><a href="http://www.open-std.org/jtc1/sc22/wg21" target="_top"><span class="bold"><strong>C++
Standards Committee's current Working Paper</strong></span></a></span></dt>
<dd><p>
</dl>
</div>
</div>
+<div class="footnotes">
+<br><hr style="width:100; text-align:left;margin-left: 0">
+<div id="ftn.chrono.users_guide.tutorial.i_o.duration_io.f0" class="footnote"><p><a href="#chrono.users_guide.tutorial.i_o.duration_io.f0" class="para"><sup class="para">[1] </sup></a>
+ <a class="link" href="reference.html#chrono.reference.io_v1.chrono_io_hpp.manipulators" title="I/O Manipulators"><code class="computeroutput"><span class="identifier">duration_short</span></code></a> in V1
+ </p></div>
+</div>
</div>
<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr>
<td align="left"></td>
-<td align="right"><div class="copyright-footer">Copyright © 2008 Howard Hinnant<br>Copyright © 2006, 2008 Beman Dawes<br>Copyright © 2009-2011 Vicente J. Botet
- Escriba<p>
+<td align="right"><div class="copyright-footer">Copyright © 2008 Howard Hinnant<br>Copyright © 2006, 2008 Beman Dawes<br>Copyright © 2009-2013 Vicente J. Botet Escriba<p>
Distributed under the Boost Software License, Version 1.0. (See accompanying
file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
</p>
projects / platform / upstream / boost.git / blobdiff