Re3: Pure Perl Internals (with Pure Perl Segfaults)

[blakem]

Ingy needed a pure Perl method of determining if a scalar contained an integer or a string

While his results are cool, he could have saved a lot of work if he'd asked around to see if anyone had already found a solution to this problem (note the unary "~", it's important)

sub is_integer { ~$_[0] !~ /\D/ }

Here are some tests to demonstrate that it works:

#!/usr/bin/perl -wT
use strict;
use Test;
BEGIN { plan tests => 345 }

for my $num (-56789, -300, -1, 0..100, 5345, 6574572, 23457356) {
  ok( is_integer($num) );
  my $string = "$num";
  ok( not is_integer($string) );
}

for my $string ((map { chr($_) } 0..127), 'dog', 'cat', 'mouse') {
  ok( not is_integer($string) );
}

sub is_integer { ~$_[0] !~ /\D/ }

I found the is_integer() implementation in my cool-snippets-from-perlmonks directory, but can't seem to find the original thread.....