Substitution operator troubles

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

Hello Monks, I seek you great wisdom. I'm fighting with a regex. The code:


 while(defined ($file = readdir(DIR))) {
    next if $file =~ /^\.\.?$/; 
    if ($file =~ /_s_/) {
      $file = "../human/chr".$c.".fa/$file";
      foreach $tool (@$tools) {
    print $file,"\n";              #  <------ line 1
     $tool =~ s/<infile>/$file/;   #  <------ line 2
     print $tool,"\n";             #  <------ line 3
      }
    }
  }
[download]

Line 1 prints what I want. Line 3 prints only the first occurance of $file, so I'm guessing that the regex is only being compiled once with the first $file it "sees". My question: How the heck do I get the substitution to work for each value of $file, not just the first? Thanks Monks.

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Re: Substitution operator troubles by chromatic (Archbishop) on Jun 03, 2003 at 21:11 UTC
You're changing the array elements in-place. Once you've substituted away `<infile>`, it's gone for good. You could instead work on copies of the array elements: `foreach my $tool (@$tools) { my $edit_tool = $tool; $edit_tool =~ s/<infile>/$file/ or next; }` [download]	[reply] [d/l] [select]
Re: Substitution operator troubles by cbro (Pilgrim) on Jun 03, 2003 at 20:56 UTC
As far as I can tell you are only missing the global flag. That is: `$tool =~ s/<infile>/$file/;` [download] Should be: `$tool =~ s/<infile>/$file/g;` [download]	[reply] [d/l] [select]