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  24 <a href="#glib-Warnings-and-Assertions.synopsis" class="shortcut">Top</a>
  25                    |
  26                   <a href="#glib-Warnings-and-Assertions.description" class="shortcut">Description</a>
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  29 <div class="refentry">
  30 <a name="glib-Warnings-and-Assertions"></a><div class="titlepage"></div>
  31 <div class="refnamediv"><table width="100%"><tr>
  32 <td valign="top">
  33 <h2><span class="refentrytitle"><a name="glib-Warnings-and-Assertions.top_of_page"></a>Message Output and Debugging Functions</span></h2>
  34 <p>Message Output and Debugging Functions — functions to output messages and help debug applications</p>
  35 </td>
  36 <td valign="top" align="right"></td>
  37 </tr></table></div>
  38 <div class="refsynopsisdiv">
  39 <a name="glib-Warnings-and-Assertions.synopsis"></a><h2>Synopsis</h2>
  40 <pre class="synopsis">
  41 #include &lt;glib.h&gt;
  42
  43 <span class="returnvalue">void</span>                <a class="link" href="glib-Warnings-and-Assertions.html#g-print" title="g_print ()">g_print</a>                             (<em class="parameter"><code>const <a class="link" href="glib-Basic-Types.html#gchar" title="gchar"><span class="type">gchar</span></a> *format</code></em>,
  44                                                          <em class="parameter"><code>...</code></em>);
  45 <a class="link" href="glib-Warnings-and-Assertions.html#GPrintFunc" title="GPrintFunc ()"><span class="returnvalue">GPrintFunc</span></a>          <a class="link" href="glib-Warnings-and-Assertions.html#g-set-print-handler" title="g_set_print_handler ()">g_set_print_handler</a>                 (<em class="parameter"><code><a class="link" href="glib-Warnings-and-Assertions.html#GPrintFunc" title="GPrintFunc ()"><span class="type">GPrintFunc</span></a> func</code></em>);
  46 <span class="returnvalue">void</span>                (<a class="link" href="glib-Warnings-and-Assertions.html#GPrintFunc" title="GPrintFunc ()">*GPrintFunc</a>)                       (<em class="parameter"><code>const <a class="link" href="glib-Basic-Types.html#gchar" title="gchar"><span class="type">gchar</span></a> *string</code></em>);
  47
  48 <span class="returnvalue">void</span>                <a class="link" href="glib-Warnings-and-Assertions.html#g-printerr" title="g_printerr ()">g_printerr</a>                          (<em class="parameter"><code>const <a class="link" href="glib-Basic-Types.html#gchar" title="gchar"><span class="type">gchar</span></a> *format</code></em>,
  49                                                          <em class="parameter"><code>...</code></em>);
  50 <a class="link" href="glib-Warnings-and-Assertions.html#GPrintFunc" title="GPrintFunc ()"><span class="returnvalue">GPrintFunc</span></a>          <a class="link" href="glib-Warnings-and-Assertions.html#g-set-printerr-handler" title="g_set_printerr_handler ()">g_set_printerr_handler</a>              (<em class="parameter"><code><a class="link" href="glib-Warnings-and-Assertions.html#GPrintFunc" title="GPrintFunc ()"><span class="type">GPrintFunc</span></a> func</code></em>);
  51
  52 #define             <a class="link" href="glib-Warnings-and-Assertions.html#g-return-if-fail" title="g_return_if_fail()">g_return_if_fail</a>                    (expr)
  53 #define             <a class="link" href="glib-Warnings-and-Assertions.html#g-return-val-if-fail" title="g_return_val_if_fail()">g_return_val_if_fail</a>                (expr,
  54                                                          val)
  55 #define             <a class="link" href="glib-Warnings-and-Assertions.html#g-return-if-reached" title="g_return_if_reached">g_return_if_reached</a>
  56 #define             <a class="link" href="glib-Warnings-and-Assertions.html#g-return-val-if-reached" title="g_return_val_if_reached()">g_return_val_if_reached</a>             (val)
  57 #define             <a class="link" href="glib-Warnings-and-Assertions.html#g-warn-if-fail" title="g_warn_if_fail()">g_warn_if_fail</a>                      (expr)
  58 #define             <a class="link" href="glib-Warnings-and-Assertions.html#g-warn-if-reached" title="g_warn_if_reached">g_warn_if_reached</a>
  59
  60 <span class="returnvalue">void</span>                <a class="link" href="glib-Warnings-and-Assertions.html#g-on-error-query" title="g_on_error_query ()">g_on_error_query</a>                    (<em class="parameter"><code>const <a class="link" href="glib-Basic-Types.html#gchar" title="gchar"><span class="type">gchar</span></a> *prg_name</code></em>);
  61 <span class="returnvalue">void</span>                <a class="link" href="glib-Warnings-and-Assertions.html#g-on-error-stack-trace" title="g_on_error_stack_trace ()">g_on_error_stack_trace</a>              (<em class="parameter"><code>const <a class="link" href="glib-Basic-Types.html#gchar" title="gchar"><span class="type">gchar</span></a> *prg_name</code></em>);
  62
  63 #define             <a class="link" href="glib-Warnings-and-Assertions.html#G-BREAKPOINT:CAPS" title="G_BREAKPOINT">G_BREAKPOINT</a>
  64 </pre>
  65 </div>
  66 <div class="refsect1">
  67 <a name="glib-Warnings-and-Assertions.description"></a><h2>Description</h2>
  68 <p>
  69 These functions provide support for outputting messages.
  70 </p>
  71 <p>
  72 The <code class="function">g_return</code> family of macros (<a class="link" href="glib-Warnings-and-Assertions.html#g-return-if-fail" title="g_return_if_fail()"><code class="function">g_return_if_fail()</code></a>,
  73 <a class="link" href="glib-Warnings-and-Assertions.html#g-return-val-if-fail" title="g_return_val_if_fail()"><code class="function">g_return_val_if_fail()</code></a>, <a class="link" href="glib-Warnings-and-Assertions.html#g-return-if-reached" title="g_return_if_reached"><code class="function">g_return_if_reached()</code></a>, <a class="link" href="glib-Warnings-and-Assertions.html#g-return-val-if-reached" title="g_return_val_if_reached()"><code class="function">g_return_val_if_reached()</code></a>)
  74 should only be used for programming errors, a typical use case is
  75 checking for invalid parameters at the beginning of a public function.
  76 They should not be used if you just mean "if (error) return", they
  77 should only be used if you mean "if (bug in program) return".
  78 The program behavior is generally considered undefined after one
  79 of these checks fails. They are not intended for normal control
  80 flow, only to give a perhaps-helpful warning before giving up.
  81 </p>
  82 </div>
  83 <div class="refsect1">
  84 <a name="glib-Warnings-and-Assertions.details"></a><h2>Details</h2>
  85 <div class="refsect2">
  86 <a name="g-print"></a><h3>g_print ()</h3>
  87 <pre class="programlisting"><span class="returnvalue">void</span>                g_print                             (<em class="parameter"><code>const <a class="link" href="glib-Basic-Types.html#gchar" title="gchar"><span class="type">gchar</span></a> *format</code></em>,
  88                                                          <em class="parameter"><code>...</code></em>);</pre>
  89 <p>
  90 Outputs a formatted message via the print handler.
  91 The default print handler simply outputs the message to stdout.
  92 </p>
  93 <p>
  94 <a class="link" href="glib-Warnings-and-Assertions.html#g-print" title="g_print ()"><code class="function">g_print()</code></a> should not be used from within libraries for debugging
  95 messages, since it may be redirected by applications to special
  96 purpose message windows or even files. Instead, libraries should
  97 use <a class="link" href="glib-Message-Logging.html#g-log" title="g_log ()"><code class="function">g_log()</code></a>, or the convenience functions <a class="link" href="glib-Message-Logging.html#g-message" title="g_message()"><code class="function">g_message()</code></a>, <a class="link" href="glib-Message-Logging.html#g-warning" title="g_warning()"><code class="function">g_warning()</code></a>
  98 and <a class="link" href="glib-Message-Logging.html#g-error" title="g_error()"><code class="function">g_error()</code></a>.
  99 </p>
 100 <div class="variablelist"><table border="0">
 101 <col align="left" valign="top">
 102 <tbody>
 103 <tr>
 104 <td><p><span class="term"><em class="parameter"><code>format</code></em> :</span></p></td>
 105 <td>the message format. See the <code class="function">printf()</code> documentation</td>
 106 </tr>
 107 <tr>
 108 <td><p><span class="term"><em class="parameter"><code>...</code></em> :</span></p></td>
 109 <td>the parameters to insert into the format string</td>
 110 </tr>
 111 </tbody>
 112 </table></div>
 113 </div>
 114 <hr>
 115 <div class="refsect2">
 116 <a name="g-set-print-handler"></a><h3>g_set_print_handler ()</h3>
 117 <pre class="programlisting"><a class="link" href="glib-Warnings-and-Assertions.html#GPrintFunc" title="GPrintFunc ()"><span class="returnvalue">GPrintFunc</span></a>          g_set_print_handler                 (<em class="parameter"><code><a class="link" href="glib-Warnings-and-Assertions.html#GPrintFunc" title="GPrintFunc ()"><span class="type">GPrintFunc</span></a> func</code></em>);</pre>
 118 <p>
 119 Sets the print handler.
 120 </p>
 121 <p>
 122 Any messages passed to <a class="link" href="glib-Warnings-and-Assertions.html#g-print" title="g_print ()"><code class="function">g_print()</code></a> will be output via
 123 the new handler. The default handler simply outputs
 124 the message to stdout. By providing your own handler
 125 you can redirect the output, to a GTK+ widget or a
 126 log file for example.
 127 </p>
 128 <div class="variablelist"><table border="0">
 129 <col align="left" valign="top">
 130 <tbody>
 131 <tr>
 132 <td><p><span class="term"><em class="parameter"><code>func</code></em> :</span></p></td>
 133 <td>the new print handler</td>
 134 </tr>
 135 <tr>
 136 <td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
 137 <td>the old print handler</td>
 138 </tr>
 139 </tbody>
 140 </table></div>
 141 </div>
 142 <hr>
 143 <div class="refsect2">
 144 <a name="GPrintFunc"></a><h3>GPrintFunc ()</h3>
 145 <pre class="programlisting"><span class="returnvalue">void</span>                (*GPrintFunc)                       (<em class="parameter"><code>const <a class="link" href="glib-Basic-Types.html#gchar" title="gchar"><span class="type">gchar</span></a> *string</code></em>);</pre>
 146 <p>
 147 Specifies the type of the print handler functions.
 148 These are called with the complete formatted string to output.
 149 </p>
 150 <div class="variablelist"><table border="0">
 151 <col align="left" valign="top">
 152 <tbody><tr>
 153 <td><p><span class="term"><em class="parameter"><code>string</code></em> :</span></p></td>
 154 <td>the message to output</td>
 155 </tr></tbody>
 156 </table></div>
 157 </div>
 158 <hr>
 159 <div class="refsect2">
 160 <a name="g-printerr"></a><h3>g_printerr ()</h3>
 161 <pre class="programlisting"><span class="returnvalue">void</span>                g_printerr                          (<em class="parameter"><code>const <a class="link" href="glib-Basic-Types.html#gchar" title="gchar"><span class="type">gchar</span></a> *format</code></em>,
 162                                                          <em class="parameter"><code>...</code></em>);</pre>
 163 <p>
 164 Outputs a formatted message via the error message handler.
 165 The default handler simply outputs the message to stderr.
 166 </p>
 167 <p>
 168 <a class="link" href="glib-Warnings-and-Assertions.html#g-printerr" title="g_printerr ()"><code class="function">g_printerr()</code></a> should not be used from within libraries.
 169 Instead <a class="link" href="glib-Message-Logging.html#g-log" title="g_log ()"><code class="function">g_log()</code></a> should be used, or the convenience functions
 170 <a class="link" href="glib-Message-Logging.html#g-message" title="g_message()"><code class="function">g_message()</code></a>, <a class="link" href="glib-Message-Logging.html#g-warning" title="g_warning()"><code class="function">g_warning()</code></a> and <a class="link" href="glib-Message-Logging.html#g-error" title="g_error()"><code class="function">g_error()</code></a>.
 171 </p>
 172 <div class="variablelist"><table border="0">
 173 <col align="left" valign="top">
 174 <tbody>
 175 <tr>
 176 <td><p><span class="term"><em class="parameter"><code>format</code></em> :</span></p></td>
 177 <td>the message format. See the <code class="function">printf()</code> documentation</td>
 178 </tr>
 179 <tr>
 180 <td><p><span class="term"><em class="parameter"><code>...</code></em> :</span></p></td>
 181 <td>the parameters to insert into the format string</td>
 182 </tr>
 183 </tbody>
 184 </table></div>
 185 </div>
 186 <hr>
 187 <div class="refsect2">
 188 <a name="g-set-printerr-handler"></a><h3>g_set_printerr_handler ()</h3>
 189 <pre class="programlisting"><a class="link" href="glib-Warnings-and-Assertions.html#GPrintFunc" title="GPrintFunc ()"><span class="returnvalue">GPrintFunc</span></a>          g_set_printerr_handler              (<em class="parameter"><code><a class="link" href="glib-Warnings-and-Assertions.html#GPrintFunc" title="GPrintFunc ()"><span class="type">GPrintFunc</span></a> func</code></em>);</pre>
 190 <p>
 191 Sets the handler for printing error messages.
 192 </p>
 193 <p>
 194 Any messages passed to <a class="link" href="glib-Warnings-and-Assertions.html#g-printerr" title="g_printerr ()"><code class="function">g_printerr()</code></a> will be output via
 195 the new handler. The default handler simply outputs the
 196 message to stderr. By providing your own handler you can
 197 redirect the output, to a GTK+ widget or a log file for
 198 example.
 199 </p>
 200 <div class="variablelist"><table border="0">
 201 <col align="left" valign="top">
 202 <tbody>
 203 <tr>
 204 <td><p><span class="term"><em class="parameter"><code>func</code></em> :</span></p></td>
 205 <td>the new error message handler</td>
 206 </tr>
 207 <tr>
 208 <td><p><span class="term"><span class="emphasis"><em>Returns</em></span> :</span></p></td>
 209 <td>the old error message handler</td>
 210 </tr>
 211 </tbody>
 212 </table></div>
 213 </div>
 214 <hr>
 215 <div class="refsect2">
 216 <a name="g-return-if-fail"></a><h3>g_return_if_fail()</h3>
 217 <pre class="programlisting">#define             g_return_if_fail(expr)</pre>
 218 <p>
 219 Verifies that the expression evaluates to <a class="link" href="glib-Standard-Macros.html#TRUE:CAPS" title="TRUE"><code class="literal">TRUE</code></a>.  If the expression
 220 evaluates to <a class="link" href="glib-Standard-Macros.html#FALSE:CAPS" title="FALSE"><code class="literal">FALSE</code></a>, a critical message is logged and the current
 221 function returns.  This can only be used in functions which do not
 222 return a value.
 223 </p>
 224 <p>
 225 If G_DISABLE_CHECKS is defined then the check is not performed.  You
 226 should therefore not depend on any side effects of <em class="parameter"><code>expr</code></em>.
 227 </p>
 228 <div class="variablelist"><table border="0">
 229 <col align="left" valign="top">
 230 <tbody><tr>
 231 <td><p><span class="term"><em class="parameter"><code>expr</code></em> :</span></p></td>
 232 <td>the expression to check</td>
 233 </tr></tbody>
 234 </table></div>
 235 </div>
 236 <hr>
 237 <div class="refsect2">
 238 <a name="g-return-val-if-fail"></a><h3>g_return_val_if_fail()</h3>
 239 <pre class="programlisting">#define             g_return_val_if_fail(expr,val)</pre>
 240 <p>
 241 Verifies that the expression evaluates to <a class="link" href="glib-Standard-Macros.html#TRUE:CAPS" title="TRUE"><code class="literal">TRUE</code></a>.  If the expression
 242 evaluates to <a class="link" href="glib-Standard-Macros.html#FALSE:CAPS" title="FALSE"><code class="literal">FALSE</code></a>, a critical message is logged and <em class="parameter"><code>val</code></em> is
 243 returned from the current function.
 244 </p>
 245 <p>
 246 If G_DISABLE_CHECKS is defined then the check is not performed.  You
 247 should therefore not depend on any side effects of <em class="parameter"><code>expr</code></em>.
 248 </p>
 249 <div class="variablelist"><table border="0">
 250 <col align="left" valign="top">
 251 <tbody>
 252 <tr>
 253 <td><p><span class="term"><em class="parameter"><code>expr</code></em> :</span></p></td>
 254 <td>the expression to check</td>
 255 </tr>
 256 <tr>
 257 <td><p><span class="term"><em class="parameter"><code>val</code></em> :</span></p></td>
 258 <td>the value to return from the current function
 259 if the expression is not true</td>
 260 </tr>
 261 </tbody>
 262 </table></div>
 263 </div>
 264 <hr>
 265 <div class="refsect2">
 266 <a name="g-return-if-reached"></a><h3>g_return_if_reached</h3>
 267 <pre class="programlisting">#define             g_return_if_reached()</pre>
 268 <p>
 269 Logs a critical message and returns from the current function.
 270 This can only be used in functions which do not return a value.
 271 </p>
 272 </div>
 273 <hr>
 274 <div class="refsect2">
 275 <a name="g-return-val-if-reached"></a><h3>g_return_val_if_reached()</h3>
 276 <pre class="programlisting">#define             g_return_val_if_reached(val)</pre>
 277 <p>
 278 Logs a critical message and returns <em class="parameter"><code>val</code></em>.
 279 </p>
 280 <div class="variablelist"><table border="0">
 281 <col align="left" valign="top">
 282 <tbody><tr>
 283 <td><p><span class="term"><em class="parameter"><code>val</code></em> :</span></p></td>
 284 <td>the value to return from the current function</td>
 285 </tr></tbody>
 286 </table></div>
 287 </div>
 288 <hr>
 289 <div class="refsect2">
 290 <a name="g-warn-if-fail"></a><h3>g_warn_if_fail()</h3>
 291 <pre class="programlisting">#define             g_warn_if_fail(expr)</pre>
 292 <p>
 293 Logs a warning if the expression is not true.
 294 </p>
 295 <div class="variablelist"><table border="0">
 296 <col align="left" valign="top">
 297 <tbody><tr>
 298 <td><p><span class="term"><em class="parameter"><code>expr</code></em> :</span></p></td>
 299 <td>the expression to check</td>
 300 </tr></tbody>
 301 </table></div>
 302 <p class="since">Since 2.16</p>
 303 </div>
 304 <hr>
 305 <div class="refsect2">
 306 <a name="g-warn-if-reached"></a><h3>g_warn_if_reached</h3>
 307 <pre class="programlisting">#define             g_warn_if_reached()</pre>
 308 <p>
 309 Logs a critical warning.
 310 </p>
 311 <p class="since">Since 2.16</p>
 312 </div>
 313 <hr>
 314 <div class="refsect2">
 315 <a name="g-on-error-query"></a><h3>g_on_error_query ()</h3>
 316 <pre class="programlisting"><span class="returnvalue">void</span>                g_on_error_query                    (<em class="parameter"><code>const <a class="link" href="glib-Basic-Types.html#gchar" title="gchar"><span class="type">gchar</span></a> *prg_name</code></em>);</pre>
 317 <p>
 318 Prompts the user with
 319 <code class="computeroutput">[E]xit, [H]alt, show [S]tack trace or [P]roceed</code>.
 320 This function is intended to be used for debugging use only.
 321 The following example shows how it can be used together with
 322 the <a class="link" href="glib-Message-Logging.html#g-log" title="g_log ()"><code class="function">g_log()</code></a> functions.
 323 </p>
 324 <p>
 325 </p>
 326 <div class="informalexample">
 327   <table class="listing_frame" border="0" cellpadding="0" cellspacing="0">
 328     <tbody>
 329       <tr>
 330         <td class="listing_lines" align="right"><pre>1
 331 2
 332 3
 333 4
 334 5
 335 6
 336 7
 337 8
 338 9
 339 10
 340 11
 341 12
 342 13
 343 14
 344 15
 345 16
 346 17
 347 18
 348 19
 349 20
 350 21
 351 22
 352 23</pre></td>
 353         <td class="listing_code"><pre class="programlisting"><span class="preproc">#include</span><span class="normal"> </span><span class="string">&lt;glib.h&gt;</span>
 354
 355 <span class="keyword">static</span><span class="normal"> </span><span class="type">void</span>
 356 <span class="function">log_handler</span><span class="normal"> </span><span class="symbol">(</span><span class="keyword">const</span><span class="normal"> </span><span class="usertype">gchar</span><span class="normal">   </span><span class="symbol">*</span><span class="normal">log_domain</span><span class="symbol">,</span>
 357 <span class="normal">             </span><span class="usertype">GLogLevelFlags</span><span class="normal"> log_level</span><span class="symbol">,</span>
 358 <span class="normal">             </span><span class="keyword">const</span><span class="normal"> </span><span class="usertype">gchar</span><span class="normal">   </span><span class="symbol">*</span><span class="normal">message</span><span class="symbol">,</span>
 359 <span class="normal">             </span><span class="usertype">gpointer</span><span class="normal">       user_data</span><span class="symbol">)</span>
 360 <span class="cbracket">{</span>
 361 <span class="normal">  </span><span class="function"><a href="glib-Message-Logging.html#g-log-default-handler">g_log_default_handler</a></span><span class="normal"> </span><span class="symbol">(</span><span class="normal">log_domain</span><span class="symbol">,</span><span class="normal"> log_level</span><span class="symbol">,</span><span class="normal"> message</span><span class="symbol">,</span><span class="normal"> user_data</span><span class="symbol">);</span>
 362
 363 <span class="normal">  </span><span class="function"><a href="glib-Warnings-and-Assertions.html#g-on-error-query">g_on_error_query</a></span><span class="normal"> </span><span class="symbol">(</span><span class="normal">MY_PROGRAM_NAME</span><span class="symbol">);</span>
 364 <span class="cbracket">}</span>
 365
 366 <span class="type">int</span>
 367 <span class="function">main</span><span class="normal"> </span><span class="symbol">(</span><span class="type">int</span><span class="normal"> argc</span><span class="symbol">,</span><span class="normal"> </span><span class="type">char</span><span class="normal"> </span><span class="symbol">*</span><span class="normal">argv</span><span class="symbol">[])</span>
 368 <span class="cbracket">{</span>
 369 <span class="normal">  </span><span class="function"><a href="glib-Message-Logging.html#g-log-set-handler">g_log_set_handler</a></span><span class="normal"> </span><span class="symbol">(</span><span class="normal">MY_LOG_DOMAIN</span><span class="symbol">,</span>
 370 <span class="normal">                     <a href="glib-Message-Logging.html#G-LOG-LEVEL-WARNING:CAPS">G_LOG_LEVEL_WARNING</a> </span><span class="symbol">|</span>
 371 <span class="normal">                     <a href="glib-Message-Logging.html#G-LOG-LEVEL-ERROR:CAPS">G_LOG_LEVEL_ERROR</a> </span><span class="symbol">|</span>
 372 <span class="normal">                     <a href="glib-Message-Logging.html#G-LOG-LEVEL-CRITICAL:CAPS">G_LOG_LEVEL_CRITICAL</a></span><span class="symbol">,</span>
 373 <span class="normal">                     log_handler</span><span class="symbol">,</span>
 374 <span class="normal">                     <a href="glib-Standard-Macros.html#NULL:CAPS">NULL</a></span><span class="symbol">);</span>
 375 <span class="normal">  </span><span class="comment">/* ... */</span></pre></td>
 376       </tr>
 377     </tbody>
 378   </table>
 379 </div>
 380
 381 <p>
 382 </p>
 383 <p>
 384 If [E]xit is selected, the application terminates with a call
 385 to <code class="literal">_exit(0)</code>.
 386 </p>
 387 <p>
 388 If [S]tack trace is selected, <a class="link" href="glib-Warnings-and-Assertions.html#g-on-error-stack-trace" title="g_on_error_stack_trace ()"><code class="function">g_on_error_stack_trace()</code></a> is called.
 389 This invokes <span class="command"><strong>gdb</strong></span>, which attaches to the current
 390 process and shows a stack trace. The prompt is then shown again.
 391 </p>
 392 <p>
 393 If [P]roceed is selected, the function returns.
 394 </p>
 395 <p>
 396 This function may cause different actions on non-UNIX platforms.
 397 </p>
 398 <div class="variablelist"><table border="0">
 399 <col align="left" valign="top">
 400 <tbody><tr>
 401 <td><p><span class="term"><em class="parameter"><code>prg_name</code></em> :</span></p></td>
 402 <td>the program name, needed by <span class="command"><strong>gdb</strong></span>
 403 for the [S]tack trace option. If <em class="parameter"><code>prg_name</code></em> is <a class="link" href="glib-Standard-Macros.html#NULL:CAPS" title="NULL"><code class="literal">NULL</code></a>, <a class="link" href="glib-Miscellaneous-Utility-Functions.html#g-get-prgname" title="g_get_prgname ()"><code class="function">g_get_prgname()</code></a>
 404 is called to get the program name (which will work correctly if
 405 <a href="http://library.gnome.org/devel/gdk/gdk3-General.html#gdk-init"><code class="function">gdk_init()</code></a> or <a href="http://library.gnome.org/devel/gtk/gtk3-General.html#gtk-init"><code class="function">gtk_init()</code></a> has been called)</td>
 406 </tr></tbody>
 407 </table></div>
 408 </div>
 409 <hr>
 410 <div class="refsect2">
 411 <a name="g-on-error-stack-trace"></a><h3>g_on_error_stack_trace ()</h3>
 412 <pre class="programlisting"><span class="returnvalue">void</span>                g_on_error_stack_trace              (<em class="parameter"><code>const <a class="link" href="glib-Basic-Types.html#gchar" title="gchar"><span class="type">gchar</span></a> *prg_name</code></em>);</pre>
 413 <p>
 414 Invokes <span class="command"><strong>gdb</strong></span>, which attaches to the current
 415 process and shows a stack trace. Called by <a class="link" href="glib-Warnings-and-Assertions.html#g-on-error-query" title="g_on_error_query ()"><code class="function">g_on_error_query()</code></a>
 416 when the [S]tack trace option is selected. You can get the current
 417 process's "program name" with <a class="link" href="glib-Miscellaneous-Utility-Functions.html#g-get-prgname" title="g_get_prgname ()"><code class="function">g_get_prgname()</code></a>, assuming that you
 418 have called <a href="http://library.gnome.org/devel/gtk/gtk3-General.html#gtk-init"><code class="function">gtk_init()</code></a> or <a href="http://library.gnome.org/devel/gdk/gdk3-General.html#gdk-init"><code class="function">gdk_init()</code></a>.
 419 </p>
 420 <p>
 421 This function may cause different actions on non-UNIX platforms.
 422 </p>
 423 <div class="variablelist"><table border="0">
 424 <col align="left" valign="top">
 425 <tbody><tr>
 426 <td><p><span class="term"><em class="parameter"><code>prg_name</code></em> :</span></p></td>
 427 <td>the program name, needed by <span class="command"><strong>gdb</strong></span>
 428 for the [S]tack trace option.</td>
 429 </tr></tbody>
 430 </table></div>
 431 </div>
 432 <hr>
 433 <div class="refsect2">
 434 <a name="G-BREAKPOINT:CAPS"></a><h3>G_BREAKPOINT</h3>
 435 <pre class="programlisting">#  define G_BREAKPOINT()        G_STMT_START{ __asm__ __volatile__ ("int $03"); }G_STMT_END
 436 </pre>
 437 <p>
 438 Inserts a breakpoint instruction into the code.
 439 </p>
 440 <p>
 441 On x86 and alpha systems this is implemented as a soft interrupt
 442 and on other architectures it raises a <code class="literal">SIGTRAP</code> signal.
 443 </p>
 444 </div>
 445 </div>
 446 </div>
 447 <div class="footer">
 448 <hr>
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