#!/usr/bin/perl
use strict;
use warnings;

my @numbers = qw(1 -1 123.1 0.1 Characters);

foreach my $number (@numbers) {
    checkInputStringWithSwitchConditions($number);
}

sub checkInputStringWithSwitchConditions {
    use Switch;
    switch ($_[0]) {
	case /^[+-]?\d+\z/		                 { print "The $_[0] is a +/- integer\n" }
	case /^[+-]?(?=\.?\d)\d*\.?\d*(?:e[+-]?\d+)?\z/i { print "The $_[0] is a C float\n" }
	case /\D/                                        { print "The $_[0] has nondigits\n" }
	else		                                 { print "Non of the cases where True\n" }
    }
}

__END__

The 1 is a +/- integer
The -1 is a +/- integer
The 123.1 is a C float
The 0.1 is a C float
The Characters has nondigits