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