#!/usr/bin/perl -w
use strict;

my @numbers = ('-1', 1, 1000, '0001', 'abc', 34, 
 '0x65', "1.2", '3.', '.3');

sub is_numeric {
    return $_[0] =~ /^[1-9][0-9.]*$/
}

for (@numbers)
{
    if (is_numeric($_) ){
        print  "$_ is numeric\n";
    }
    else {
        print "$_ is NOT numeric\n";
    }
}
__END__
-1 is NOT numeric
1 is numeric
1000 is numeric
0001 is NOT numeric
abc is NOT numeric
34 is numeric
0x65 is NOT numeric
1.2 is numeric
3. is numeric
.3 is NOT numeric