Question

Is there an actual package in CPAN to convert such string:

my $string = "54.4M"
my $string2 = "3.2G"

into the actual number in bytes:

54,400,000
3,200,000,000

And vice versa.

In principle what I want to do at the end is to sum out all the memory size.

Answer 1

To get the exact output you asked for, use Number::FormatEng and Number::Format:

use strict;
use warnings;

use Number::FormatEng qw(:all);
use Number::Format qw(:subs);

my $string = "54.4M" ;
my $string2 = "3.2G" ;

print format_number(unformat_pref($string))  , "\n";
print format_number(unformat_pref($string2)) , "\n";

__END__
54,400,000
3,200,000,000             

By the way, only unformat_pref is needed if you are going to perform calculations with the result.

Since Number::FormatEng was intended for engineering notation conversion (not for bytes), its prefix is case-sensitive. If you want to use it for kilobytes, you must use lower case k.

Number::Format will convert these strings into actual bytes (kinda, almost).

use Number::Format qw(:subs);

my $string = "54.4M" ;
my $string2 = "3.2G" ;

print round(unformat_number($string) , 0), "\n";
print round(unformat_number($string2), 0), "\n";

__END__
57042534
3435973837

The reason I said “kinda, almost” is that Number::Format treats 1K as being equal to 1024 bytes, not 1000 bytes. That’s probably why it gives a weird-looking result (with fractional bytes), unless it is rounded.