is_numeric from perlfaq4

nop has asked for the wisdom of the Perl Monks concerning the following question:

Hi -- I grabbed the is_numeric function from perfaq4. Either I am using it wrong, or it doesn't work. The following code asserts that undef and fish are numeric. What's going wrong? Thanks -- nop

use POSIX qw(strtod);
use strict;

foreach (undef, qw(4 0 fish)) {
    print $_ , " is numeric? ", is_numeric($_), "\n";
}

sub getnum {
    my $str = shift;
    $str =~ s/^\s+//; $str =~ s/\s+$//; $! = 0;
    my($num, $unparsed) = strtod($str);
    if (($str eq '') || ($unparsed != 0) || $!) {return;} else {return
+ $num;} 
} 

sub is_numeric { defined scalar &getnum }
[download]

Comment on is_numeric from perlfaq4 Download Code

Replies are listed 'Best First'.
Re: is_numeric from perlfaq4 by Abigail-II (Bishop) on Oct 07, 2002 at 18:02 UTC
You never called the function `getnum`. All you did was returning whether the sub `getnum` was defined. Which it was. You didn't copy the `is_numeric` function correctly from the faq. It should be: `sub is_numeric {defined getnum $_ [0]}` [download] Abigail	[reply] [d/l] [select]
Re: is_numeric from perlfaq4 by thelenm (Vicar) on Oct 07, 2002 at 18:06 UTC
Are you using an older version of Perl? In perlfaq4 for 5.6.1 and 5.8.0, the `is_numeric` function looks like this (slightly different), and works correctly for your example: `sub getnum { use POSIX qw(strtod); my $str = shift; $str =~ s/^\s+//; $str =~ s/\s+$//; $! = 0; my($num, $unparsed) = strtod($str); if (($str eq '') \|\| ($unparsed != 0) \|\| $!) { return undef; } else { return $num; } } sub is_numeric { defined getnum($_[0]) }` [download] -- Mike `-- just,my${.02}`	[reply] [d/l] [select]
Re: is_numeric from perlfaq4 by fglock (Vicar) on Oct 07, 2002 at 18:08 UTC
It works if you use: `sub is_numeric { defined scalar getnum(@_) }`	[reply] [d/l]


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