in reply to How do I match lines of UP TO 40 chars BUT NO MORE in a block of text?

My reply at Re: How do I match lines of 40 characters long in a block of text? does what you want I think. Note that you don't really want to match 0 lines unless you want everything to match. Also, when you are constructing a regex, it is best to be able to state exactly what you want. I think you really want "1 to 4 lines each consisting of 0 to 40 characters followed by a newline." I've included the code from original reply below for your convenience.

/
(               # Assuming you want capture these lines.
  (?:           # Group each line.
     ^          # Beginning of the line.
     .{0,40}\n  # 0 to 40 characters followed by a newline. 
  ){1,4}        # 1 to 4 lines. (0 will permit an empty match.)
)               # Done capturing.
/mx;            # /m so that ^ anchor works, /x for comments.

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"My two cents aren't worth a dime.";
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Re: Re: How do I match lines of UP TO 40 chars BUT NO MORE in a block of text?
by kleinbiker7 (Sexton) on Sep 25, 2002 at 21:21 UTC
    Thanks! However this is not working for me! Here is my code:

    $foo = "line1line1line1line1line1line1line1line1
line2line2line2line2line2line2line2line2line2line2line2line2line2line2
+line2line2line2line2
line3line3line3line3line3line3line3line3";

if ($foo =~ /((?:^.{0,40})\n{1,4})/m)            
{ print "$1: OK\n\n"; } 


else
{print "$1: NOT OK\n\n";}

    [download]

    I get this as a result: line1line1line1line1line1line1line1line1
    : OK

    Which is not good, since line2 is greater than 40 chars.

    thanks!

[reply]
[d/l]

      Well, that's exactly what it should match. Your input matches your requirements. It has a block of text consisting of between 1 and 4 (1 in this case) lines of not more than 40 characters and an additional newline.

      Your requirements are poorly specified.

      Maybe, rather than see if your input matches such a block, you want to see if your input is such a block. If this is the case, your example input wouldn't work even if the second line had less than forty characters because your third line doesn't have a trailing newline.

      If that is what you are trying to do, try this:

      /
^               # Anchor to beginning of string.
  (?:           # Group each line.
     .{0,40}\n  # 0 to 40 characters followed by a newline. 
  ){0,4}        # 0 to 4 lines.
$               # Anchor to end of string.
/x;             # /x for comments.

      [download]
      -sauoq
"My two cents aren't worth a dime.";
[reply]
[d/l]
        WOW SAROQ! I think that finally did it! Thanks for all your help in this. As far as requests go, it is tough explaining things, and I know you gurus are excellent at responding quickly, that I get impatient. Sorry, learnt my lesson here.

        Anyway, my boss is going to test it, and lets hope it goes well for her.

        One quick question, I dont understand what the ?: at the beginning of the regex does. I took the comments out. What's the diff between these:

        1. ($foo =~ /^(?:.{0,40}\n){0,4}$/
2. ($foo =~ /^(.{0,40}\n){0,4}$/ # note no ?:

        [download]

        CHEERS MATE!
        Robert

[reply]
[d/l]

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