Hello, all:

I've been fighting this for a little while, and I'm stumped. I'm trying to pull a file apart, and for some reason, my regex works normally most of the time, but sometimes fails and I can't figure out why.

Here's an example:

$ cat bug.pl
#!/usr/bin/perl
use strict;
use warnings;

my $str = join("", map { chr }
    0x13, 0x00, 0x00, 0x00, 0xf8, 0x90, 0xbc, 0xac,
    0x3a, 0x26, 0x1c, 0x27, 0xb3, 0x22, 0x22, 0xb3,
    0xf6, 0x60, 0x23, 0x2d, 0x77, 0xbf, 0xdb, 0xda,
    0xd1, 0xad, 0x0a, 0x98, 0x1a, 0x38, 0xae, 0x76,
    0xee, 0x77, 0x66, 0x35, 0x66, 0x00, 0x65, 0x00,
    0x74, 0x00, 0x69, 0x00, 0x64, 0x00, 0x5f, 0x00,
    0x69, 0x00, 0x73, 0x00, 0x6c, 0x00, 0x61, 0x00,
    0x6e, 0x00, 0x64, 0x00, 0x5f, 0x00, 0x32, 0x00,
    0x2e, 0x00, 0x74, 0x00, 0x67, 0x00, 0x72, 0x00,
    0x00, 0x00, 0xff, 0xfe, 0x76, 0x00, 0x65, 0x00,
    0x72, 0x00, 0x73, 0x00, 0x69, 0x00, 0x6f, 0x00,
    0x6e, 0x00, 0x20, 0x00, 0x31, 0x00, 0x37, 0x00,
    0x0a, 0x00, 0x53, 0x00, 0x69, 0x00, 0x7a, 0x00,
    0x65, 0x00, 0x3a, 0x00, 0x20, 0x00, 0x34, 0x00
);

for my $c (split //, $str) {
    printf "%02x ", ord($c);
}
print "\n";

if ($str=~/^(.{36})(.*?)\0\0\0/) {
    print "Found it!\n";
}
else {
    print "?where is it?\n";
}

$ perl bug.pl
13 00 00 00 f8 90 bc ac 3a 26 
1c 27 b3 22 22 b3 f6 60 23 2d 
77 bf db da d1 ad 0a 98 1a 38 
ae 76 ee 77 66 35 66 00 65 00 
74 00 69 00 64 00 5f 00 69 00 
73 00 6c 00 61 00 6e 00 64 00 
5f 00 32 00 2e 00 74 00 67 00 
72 00 00 00 ff fe 76 00 65 00 
72 00 73 00 69 00 6f 00 6e 00 
20 00 31 00 37 00 0a 00 53 00 
69 00 7a 00 65 00 3a 00 20 00 
34 00
?where is it?

[download]

I expected to see "Found it!", as there's clearly a string of three zeroes on the eighth line. (Note: I manually inserted the line breaks in the output.)

I'm probably doing something crazy, but I can't see it.

I don't expect that it matters, but I'm running 5.14.4 (from cygwin).

...roboticus

When your only tool is a hammer, all problems look like your thumb.

In reply to Regex trouble w/ embedded 0s? by roboticus

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.