Like fruiture said, perdoc has the answer...

#!perl -w
#

use strict;

my @array = (100, 'a string!', 45.678, 0.43243, '', "", 0, "another no
+rmal string with a carriage return \n");

foreach (@array) {
    if (/\D/) {
        print "$_ contains non-digits\n";
    } elsif (/^\d+$/) {
        print "$_ is a whole number\n";
    } elsif (/^-?\d+$/) {
        print "$_ is an integer\n";
    } elsif (/^[+-]?\d+$/) {
        print "$_ is a +/- integer\n";
    } elsif (/^-?\d+\.?\d*$/) {
        print "$_ is a real number\n";
    } elsif (/^-?(?:\d+(?:\.\d*)?|\.\d+)$/) {
        print "$_ is a decimal number\n";
    } elsif (/^([+-]?)(?=\d|\.\d)\d*(\.\d*)?([Ee]([+-]?\d+))?$/) {
        print "$_ is a C float\n";
    } else {
        print "$_ not a number format I recognise, bud.\n";
    }
}
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SMiTZ