sth has asked for the wisdom of the Perl Monks concerning the following question:

I think I'm missing something here, I hope someone can't tell me why this fails, 

  DB<6> $a = 'Apr-Jun03.zip~';

  DB<7> p $a =~ /^[\w.-~]+$/

  DB<8> p $a =~ /^[~\w.-]+$/
1
  DB<9> p $a                
Apr-Jun03.zip~
  DB<10> p $a =~ /^[\w~.-]+$/
1
  DB<11> p $a =~ /^[\w.~-]+$/
1

[download]

...so if I move the '~' off the end of the character class, the match works. I can't figure out why. Any ideas?

Thanks, sth

Replies are listed 'Best First'.
Re: Regex - Char Class Question
by Enlil (Parson) on Dec 10, 2003 at 18:28 UTC
    I don't think it is so much the tilde(~)being at the end but the hyphen (-) not being on one of the ends. That is, if the hyphen is not at either end of the character class then it becomes a range for whatever two chars it is in between.This should work the same as all the others for instance:
    $a =~ /^[-\w.~]+$/

    [download]

    -enlil

[reply]
[d/l]
      See perlop. If you're going to put a ] or - character into your character class then it has to be either escaped or be placed at the front after the optional ^,
[reply]
        See perlop.

        Actually, see perlre.

        If you're going to put a ] or - character into your character class then it has to be either escaped or be placed at the front after the optional ^,

        Or placed at the end immediately before the closing square bracket.

        The relevant passage from perlre: 

             If you want either "-" or "]" itself to be a member of a
     class, put it at the start of the list (possibly after a
     "^"), or escape it with a backslash.  "-" is also taken
     literally when it is at the end of the list, just before the
     closing "]".

        [download]

        -sauoq
"My two cents aren't worth a dime.";
[reply]
[d/l]

        I knew I could escape the '-', I just wanted figure out what I was missing, was driving me nuts.

        Thanks for the reply!

[reply]

      ..Thanks Enlil! I knew it was something obvious, just needed someone to point it out to me. :-)

[reply]

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