Matching and replacing

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

Hi all I have the following code

      foreach $key (keys %method)
      {
       $message_ref->[0]=~s/$key/$method{$key}/;
      }
[download]

$message_ref->[0] contains a number between 1 and 100 and possibly some other text.I want this number to be replaced by the equivalent text listed in %method. However if the number is 23, and the for loop yields a key equal to 2 then $message_ref->[0] becomes equal to the text equivalent to 2 with the 3 at the end. Does anyone know how I can ensure 23 will only be replaced with 23's text and not 2's? Any help at all would be greatly appreciated ASAP Cheers.

Edit: Added <code> tags. larsen

Comment on Matching and replacing Select or Download Code

Replies are listed 'Best First'.
Re: Matching and replacing by benn (Vicar) on Mar 25, 2003 at 14:00 UTC
You can use word-boundary anchors like this... `$message_ref->[0] =~ s/\b$key\b/$method{$key}/;` [download] Cheers.	[reply] [d/l]
Re: Matching and replacing by davorg (Chancellor) on Mar 25, 2003 at 14:02 UTC
One quick and dirty solution would be to ensure that higher (and therefore longer) keys are substituted first. `foreach $key (sort { $b <=> $a } keys %method) { $message_ref->[0] =~ s/$key/$method{$key}/; }` [download] -- <http://www.dave.org.uk> "The first rule of Perl club is you do not talk about Perl club." -- Chip Salzenberg	[reply] [d/l]
Re: Matching and replacing by robartes (Priest) on Mar 25, 2003 at 17:13 UTC
Not directly related to your immediate question (which has already been answered adequately by other monks), but if your `$key` is always numerical, you might gain some speed by using an array instead of a hash. It's up to you to decide whether it is worth refactoring your code :) `$message_ref->[0]=~s/\b$_\b/$method[$_]/ for @method;` [download] Note that: This code is untested. You can also use davorg's method by sorting @method. Update: removed 'e' modifier from regexp - not needed. CU Robartes-	[reply] [d/l] [select]