perlfaq4: use given() in number/float/integer answer

	How do I determine whether a scalar is a number/whole/integer/float?

	David Canzi also adjusted some of the regexes. The
	real number and decimal number tests are really the
	same thing, and we don't have to capture in the float
	case.

diff --git a/pod/perlfaq4.pod b/pod/perlfaq4.pod
index e972d77..139885b 100644 (file)
--- a/pod/perlfaq4.pod
+++ b/pod/perlfaq4.pod
@@ -2506,31 +2506,39 @@ some gotchas.  See the section on Regular Expressions.
 =head2 How do I determine whether a scalar is a number/whole/integer/float?
 
 Assuming that you don't care about IEEE notations like "NaN" or
-"Infinity", you probably just want to use a regular expression.
+"Infinity", you probably just want to use a regular expression:
 
-       if (/\D/)             { print "has nondigits\n" }
-       if (/^\d+\z/)         { print "is a whole number\n" }
-       if (/^-?\d+\z/)       { print "is an integer\n" }
-       if (/^[+-]?\d+\z/)    { print "is a +/- integer\n" }
-       if (/^-?\d+\.?\d*\z/) { print "is a real number\n" }
-       if (/^-?(?:\d+(?:\.\d*)?|\.\d+)\z/) { print "is a decimal number\n" }
-       if (/^([+-]?)(?=\d|\.\d)\d*(\.\d*)?([Ee]([+-]?\d+))?\z/)
-                       { print "a C float\n" }
+       use 5.010;
+       
+       given( $number ) {
+               when( /\D/ )             
+                       { say "\thas nondigits"; continue }
+               when( /^\d+\z/ )         
+                       { say "\tis a whole number"; continue }
+               when( /^-?\d+\z/ )       
+                       { say "\tis an integer"; continue }
+               when( /^[+-]?\d+\z/ )    
+                       { say "\tis a +/- integer"; continue }
+               when( /^-?(?:\d+\.?|\.\d)\d*\z/ ) 
+                       { say "\tis a real number"; continue }
+               when( /^[+-]?(?=\.?\d)\d*\.?\d*(?:e[+-]?\d+)?\z/i)
+                       { say "\tis a C float" }
+               }
 
 There are also some commonly used modules for the task.
 L<Scalar::Util> (distributed with 5.8) provides access to perl's
 internal function C<looks_like_number> for determining whether a
-variable looks like a number.  L<Data::Types> exports functions that
+variable looks like a number. L<Data::Types> exports functions that
 validate data types using both the above and other regular
 expressions. Thirdly, there is C<Regexp::Common> which has regular
 expressions to match various types of numbers. Those three modules are
 available from the CPAN.
 
 If you're on a POSIX system, Perl supports the C<POSIX::strtod>
-function.  Its semantics are somewhat cumbersome, so here's a
-C<getnum> wrapper function for more convenient access.  This function
+function. Its semantics are somewhat cumbersome, so here's a
+C<getnum> wrapper function for more convenient access. This function
 takes a string and returns the number it found, or C<undef> for input
-that isn't a C float.  The C<is_numeric> function is a front end to
+that isn't a C float. The C<is_numeric> function is a front end to
 C<getnum> if you just want to say, "Is this a float?"
 
        sub getnum {