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Re: Recursive insertion of tags

by swkronenfeld (Hermit)
on Jul 20, 2006 at 14:52 UTC ( #562598=note: print w/replies, xml ) Need Help??

in reply to Recursive insertion of tags

gellyfish's code is the way to solve this problem, but I'll point out a couple mistakes in your code to help you avoid them in the future.

print F2 <TAG>;
You want to put TAG in quotes. The line should be print F2 "<TAG>";

This is something that using warnings would have helped you catch. Your program is attempting to read a line from the filehandle TAG, and print that to filehandle F2.
# ./ Name "main::TAG" used only once: possible typo at ./ line 9. readline() on unopened filehandle TAG at ./ line 9. readline() on unopened filehandle TAG at ./ line 9. readline() on unopened filehandle TAG at ./ line 9. readline() on unopened filehandle TAG at ./ line 9.

Also, although it isn't broken in your example, your regular expression can use some work. You are matching anything that isn't ">", and then using it in a numerical comparison. This will be a problem if you capture something non-numeric. A better idea would be to write your regex like this:
if($file =~ /<ins cnt="(\d+)">/) { for ($x=0; $x < $1; $x++) { print F2 "<TAG>"; } }
What I changed:
  • Matching on digits only for the count.
  • If $line doesn't match the pattern, your code doesn't attempt to use $1 in a for loop.
  • I removed the g modified from your regex, as I don't think you intended for it in this case.
  • Nitpicking: I changed the for loop condition from $x != $1. It does not matter for this example, but it's less likely to get caught in an infinite loop when you are doing more complex things (like possibly modifiying $x inside your loop. Note that there are more Perlish ways of writing this, including print F2 "<TAG>" for(1 .. $1).

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