Here is another way of writing this code in perhaps a more concise way. 

#!/usr/bin/perl -w

use strict;
use IO::File;

my %multipliers = (
    'KB' => 2**10,
    'MB' => 2**20,
    'GB' => 2**30,
);

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


my $valid_block_type;
my $block_size;
my $block_type;

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

    chomp($block_size);

    ($block_type) = ($block_size =~ m/([a-zA-Z]{2})$/);
    $block_type ||= 'KB';
    $block_type = uc $block_type;

    if( grep($block_type eq $_, keys %multipliers) )
    {
        $block_type = $multipliers{$block_type};
        $valid_block_type = 1;
    }
    else
    {
        print "Invalid block type specified!\n\n";
    }
}

[download]
The reason this is better, is because now you only have a single branch of logic, and you can now control this logic in one place instead of two. Anytime you have the oppurtunity to control program flow/logic at a single point in the code, take it. This approach makes the code much more maintainable.

In reply to Re: why is this code bad under -w option? by linux454
in thread why is this code bad under -w option? by Grygonos

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