If you pack a string into a variable and then unpack it, it must be equal, and that has nothing to do with writing to a file. Try this: 
$g = "0110110001101101";
$bob = pack("B*", $g);
print $g . "\n";
print unpack("B*", $bob);

[download]
You should get the same results. Now, try a file (remove the -l option of perl, as it inserts a new line): 
open(FH, ">fh");
$g = "0110110001101101";
$bob = pack("B*", $g);
print FH $bob;
close(FH);

open(FH, "fh");
read(FH, $from_file, 2);

print $g . "\n";
print unpack("B*", $from_file), "\n";

[download]
And report the results (note, I changed the bytes to be visible, now it should print "lm")

In reply to Re: Problems using pack by spurperl
in thread Problems using pack by Tanaka

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.