Re: Perl: How to match a line and print words at line immediately above it?

in reply to Perl: How to match a line and print words at line immediately above it?

The way I iterate through an array and keep track of the previous element is like so:

my $previous = '';
foreach my $line (@arrayfile) {

   if ($line =~ m/WhateverIWantToMatch/) {
       print "$previous\n" if ($previous);
   }

   $previous = $line; #### This line now becomes the previous line for
+ the next array element seeing as ALL lines in the file will be proce
+ssed
}
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This is a quick example and presumes you are not going to find a match on the first line of the file.

Comment on Re: Perl: How to match a line and print words at line immediately above it? Download Code

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Re^2: Perl: How to match a line and print words at line immediately above it? by sundialsvc4 (Abbot) on Nov 01, 2013 at 14:59 UTC
... or perhaps `my $previous = undef;` to clearly reflect that there is no previous-line, much as `NULL` (in a database column) denotes the complete absence of any value at all. Whatever makes the most sense in your particular situation.	[reply]

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