Just in case there is some confusion or misunderstanding of some of the Perl tricks used I better go through some of that code and elaborate on what's happening. Note that I've taken interesting lines in processing order rather that the order they are coded.

$firstLines{$data} = @lines;

this is a little tricksy. It creates a new entry in %firstLines that contains the index to the new line as the value and is keyed by the unique part of the line contents. @lines in scalar context returns the number of elements in the array.

if (exists $firstLines{$data})

checks to see if we've already seen a specific line.

$lines[$firstLines{$data}] .= ", $type";

builds the multiple entries for duplicated lines. Note that $firstLines{$data} returns the index number that was stored earlier.

DWIM is Perl's answer to Gödel

In reply to Re^7: Checking LInes in Text File by GrandFather
in thread Checking LInes in Text File by Anonymous Monk

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