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

Ok I have a variable eg $value
it actually contains $100
I would like perl to look at this variable $value
and ask if it contains the $ sign
if so do this
if not do that.
How may I make perl ask this.

Replies are listed 'Best First'.
Re: if contains
by Zaxo (Archbishop) on Jul 05, 2003 at 14:22 UTC

    I suspect your difficulty is in not escaping the '$', which has special meaning: 

    if ($value =~ /\$/) {
    # ...
}

    [download]

    After Compline,
    Zaxo

[reply]
[d/l]
      Actually while $ does usually have a special meaning, Perl seems to try to do the Right Thing: 
      print 'aha' if('ab$de' =~ /$/);

      [download]
      works (it does find the '$' character - actually it DOES NOT, see below). However, 
      print 'aha' if('ab$de' =~ /b$/);

      [download]
      is looking for a 'b' at the end of the string, and 
      print 'aha' if('ab$de' =~ /$d/);

      [download]
      is looking for the contents of $d anywhere in the string, which it does find as $d is empty.

      Personally I'd consider index for a simple string search like this one.


      Update: D'oh! Yes pfaut, that makes a LOT more sense. That should teach me something... 

      print 'aha' if('' =~ /$/);

      [download]
      prints 'aha' because even an empty string has an end...

      --
      I'd like to be able to assign to an luser

[reply]
[d/l]
[select]
        Actually while $ does usually have a special meaning, Perl seems to try to do the Right Thing:
        print 'aha' if('ab$de' =~ /$/);

        print 'aha' if 'abcde' =~ /$/ also prints 'aha'. I do believe it's matching end of line, not the dollar sign.

        90% of every Perl application is already written. ⇒
        dragonchild
[reply]
[d/l]
[select]
Re: if contains
by broquaint (Abbot) on Jul 05, 2003 at 16:01 UTC
    If you just want to see if a character is in a string then use the index function like so 
    my $value = '$100';

if( index($value, '$') > -1) {
  print 'found "$" in $value';
} else {
  print 'no "$" in $value';
}

__output__

found "$" in $value

    [download]
    And if you want to check it's at the begining of a string just check the return value e.g 
    my $value = '$100';

if( index($value, '$') == 0) {
  print 'found "$" at beginning of $value';
} else {
  print 'no "$" in $value';
}

__output___

found "$" at beginning of $value

    [download]
    See. index for more info.
    HTH

    _________
    broquaint

[reply]
[d/l]
[select]

Back to Seekers of Perl Wisdom