NAME

SYNOPSIS

  use Number::Bytes::Human qw(format_bytes parse_bytes);
  $size = format_bytes(0); # '0'
  $size = format_bytes(2*1024); # '2.0K'

  $size = format_bytes(1_234_890, bs => 1000); # '1.3M'
  $size = format_bytes(1E9, bs => 1000); # '1.0G'

  my $bytes = parse_bytes('1.0K');   # 1024
  my $bytes = parse_bytes('1.0KB');  # 1000, SI unit
  my $bytes = parse_bytes('1.0KiB'); # 1024, SI unit

  # the OO way
  $human = Number::Bytes::Human->new(bs => 1000, si => 1);
  $size = $human->format(1E7); # '10MB'

  $bytes = $human->parse('10MB');   # 10*1000*1000
  $bytes = $human->parse('10MiB');  # 10*1024*1024
  $bytes = $human->parse('10M');    # Error, no SI unit

  $human->set_options(zero => '-');
  $size = $human->format(0);    # '-'
  $bytes = $human->parse('-');  # 0

  $human = Number::Bytes::Human->new(bs => 1000, round_style => 'round', precision => 2);
  $size = $human->format(10240000); # '10.24MB'

DESCRIPTION

This module provides a formatter which turns byte counts to usual readable format, like '2.0K', '3.1G', '100B'. It was inspired in the "-h" option of Unix utilities like "du", "df" and "ls" for "human-readable" output.

From the FreeBSD man page of "df": http://www.freebsd.org/cgi/man.cgi?query=df

  "Human-readable" output.  Use unit suffixes: Byte, Kilobyte,
  Megabyte, Gigabyte, Terabyte and Petabyte in order to reduce the
  number of digits to four or fewer using base 2 for sizes.

  byte      B
  kilobyte  K = 2**10 B = 1024 B
  megabyte  M = 2**20 B = 1024 * 1024 B
  gigabyte  G = 2**30 B = 1024 * 1024 * 1024 B
  terabyte  T = 2**40 B = 1024 * 1024 * 1024 * 1024 B

  petabyte  P = 2**50 B = 1024 * 1024 * 1024 * 1024 * 1024 B
  exabyte   E = 2**60 B = 1024 * 1024 * 1024 * 1024 * 1024 * 1024 B
  zettabyte Z = 2**70 B = 1024 * 1024 * 1024 * 1024 * 1024 * 1024 * 1024 B
  yottabyte Y = 2**80 B = 1024 * 1024 * 1024 * 1024 * 1024 * 1024 * 1024 * 1024 B

I have found this link to be quite useful:

  http://www.t1shopper.com/tools/calculate/

If you feel like a hard-drive manufacturer, you can start counting bytes by powers of 1000 (instead of the generous 1024). Just use "bs => 1000".

But if you are a floppy disk manufacturer and want to start counting in units of 1024000 (for your "1.44 MB" disks)? Then use "bs => 1_024_000".

If you feel like a purist academic, you can force the use of metric prefixes according to the Dec 1998 standard by the IEC. Never mind the units for base 1000 are "('B', 'kB', 'MB', 'GB', 'TB', 'PB', 'EB', 'ZB', 'YB')" and, even worse, the ones for base 1024 are "('B', 'KiB', 'MiB', 'GiB', 'TiB', 'PiB', 'EiB', 'ZiB', 'YiB')" with the horrible names: bytes, kibibytes, mebibytes, etc. All you have to do is to use "si => 1". Ain't that beautiful the SI system? Read about it:

  http://physics.nist.gov/cuu/Units/binary.html

You can try a pure Perl "ls -lh"-inspired command with the one-liner, er, two-liner:

  $ perl -MNumber::Bytes::Human=format_bytes \
         -e 'printf "%5s %s\n", format_bytes(-s), $_ for @ARGV' *

Why to write such a module? Because if people can write such things in C, it can be written much easier in Perl and then reused, refactored, abused. And then, when it is much improved, some brave soul can port it back to C (if only for the warm feeling of painful programming).

It is also possible to parse human readable formatted bytes. The automatic format detection recognizes SI units with the blocksizes of 1000 and 1024 respectively and additionally the customary K / M / G etc. with blocksize 1024. When si => 1 is added to the options only SI units are recognized. Explicitly specifying a blocksize changes it for all detected units.

  for (@sizes) {
    my $fmt_size = format_bytes($_, @args);
    ...
  }

  my $human = Number::Format::Bytes->new(@args);
  for (@sizes) {
    my $fmt_size = $human->format($_);
    ...
  }

DIAGNOSTICS

  "unknown round style '$style'";

  "invalid base: $block (should be 1024, 1000 or 1024000)";

  "round function ($args{round_function}) should be a code ref";

  "suffixes ($args{suffixes}) should be 1000, 1024, 1024000 or an array ref";

  "negative numbers are not allowed" (??)

SEE ALSO

The "_convert()" solution by COG in Filesys::DiskUsage.

BUGS

AUTHOR

Dagobert Michelsen, <dagobert@cpan.org>

COPYRIGHT AND LICENSE

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself.