use strict;
use warnings;

my %is_valid_type = do {
    my $i = 1;
    map { $_ => 10 * $i++ } qw( KB MB GB )
};

print "Enter the pathname and filename of the file to split: ";
my $filename = <STDIN>;
chomp($filename);

my %block = map { $_ => undef } qw( size type amount );

while (1)
{
    print "Enter the block size \n (example: 400KB,10MB,1GB): ";
    chomp($block{size} = <STDIN>);

    @block{qw(amount type)} = ($block{size} =~ m/^\s*([\d.]+)\s*([a-zA-Z]{2})\s*$/);
    $block{type} ||= 'KB';
    $block{type} = uc $block_type;

    unless ( $is_valid_type{$block{type}} )
    {
        print "Invalid block type specified!\n\n";
        next;
    }

    $block{size} = 2 ** $is_valid_type{$block{type}};
    last;
}