use 5.010;
given( $number ) {
    when( /\D/ )
        { say "\thas nondigits"; continue }
    when( /^\d+\z/ )
        { say "\tis a whole number"; continue }
    when( /^-?\d+\z/ )
        { say "\tis an integer"; continue }
    when( /^[+-]?\d+\z/ )
        { say "\tis a +/- integer"; continue }
    when( /^-?(?:\d+\.?|\.\d)\d*\z/ )
        { say "\tis a real number"; continue }
    when( /^[+-]?(?=\.?\d)\d*\.?\d*(?:e[+-]?\d+)?\z/i)
        { say "\tis a C float" }
}

##</code><code>##

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

my @numbers = (1, -1, 123.1, 0.1);

foreach my $number (@numbers) {
    if ($number =~ /\D/ ) { 
	print "The $number has nondigits\n"; 
    }
    elsif ($number =~ /^\d+\z/ ) { 
	print "The $number is a whole number\n";
    }
    elsif ($number =~ /^-?\d+\z/ ) { 
	print "The $number is an integer\n"; 
    }
    elsif ($number =~ /^[+-]?\d+\z/ ) { 
	print "The $number is a +/- integer\n"; 
    }
    elsif ($number =~ /^-?(?:\d+\.?|\.\d)\d*\z/ ) { 
	print "The $number is a real number\n"; 
    }
    elsif ($number =~ /^[+-]?(?=\.?\d)\d*\.?\d*(?:e[+-]?\d+)?\z/i ) { 
	print "The $number is a C float\n"; 
    }
}

##</code><code>##

The 1 is a whole number
The -1 has nondigits
The 123.1 has nondigits
The 0.1 has nondigits

##</code><code>##

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

##</code><code>##

my @numbers = ("1", "-1", "123.1", "0.1");

foreach my $number (@numbers) {
    my $integer = is_integer($number);
    print "$number is Integer\n" if ($integer);

    my $float = is_float($number);
    print "$number is Float\n" if ($float);
}

sub is_integer { $_[0] =~ /^[+-]?\d+$/ }
sub is_float   { $_[0] =~ /^[+-]?\d+\.?\d*$/ }

__END__

Output:

1 is Integer
1 is Float
-1 is Integer
-1 is Float
123.1 is Float
0.1 is Float

##</code><code>##

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

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

foreach my $number (@numbers) {
    if ($number =~ /^[+-]?\d+\z/ ) { 
	print "The $number is a +/- integer\n"; 
    }
    elsif ($number =~ /^[+-]?(?=\.?\d)\d*\.?\d*(?:e[+-]?\d+)?\z/i ) { 
	print "The $number is a C float\n"; 
    }
    elsif ($number =~ /\D/ ) { 
	print "The $number has nondigits\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

##</code><code>##

#!/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

##</code><code>##

#!/usr/bin/perl
use strict;
use warnings;
use Benchmark qw( timethese cmpthese ) ;

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

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

my $ifAndElsIfRefLoop = 'foreach my $number (@numbers) {
    checkInputStringWithIfAndElseConditions($number);
}';

my $Benchmark = timethese( -10, {
    IfAndElsIfLoop => $ifAndElsIfRefLoop,
    SwitchLoop => $swithRefLoop,
			   } );
cmpthese $Benchmark;

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" }
    }
}

sub checkInputStringWithIfAndElseConditions {
    if ( $_[0] =~ /^[+-]?\d+\z/ ) {
	print "The $_[0] is a +/- integer\n";
    }
    elsif ( $_[0] =~ /^[+-]?(?=\.?\d)\d*\.?\d*(?:e[+-]?\d+)?\z/i ) {
	print "The $_[0] is a C float\n";
    }
    elsif ( $_[0] =~ /\D/ ) {
	print "The $_[0] has nondigits\n";
    }
}

__END__

Benchmark: running IfAndElsIfLoop, SwitchLoop for at least 10 CPU seconds...
IfAndElsIfLoop: 11 wallclock secs (10.04 usr + -0.00 sys = 10.04 CPU) @ 4954765.54/s (n=49745846)
SwitchLoop:  9 wallclock secs (10.04 usr +  0.00 sys = 10.04 CPU) @ 5691789.84/s (n=57145570)
                    Rate IfAndElsIfLoop     SwitchLoop
IfAndElsIfLoop 4954766/s             --           -13%
SwitchLoop     5691790/s            15%             --