http://qs321.pair.com?node_id=1016354


in reply to Parse chat & File::find

You often need to do something to a line depending on what is on the next line. One way to go is to store a line, move to the next line, decide what to do and then store the current line as appropriate.
#! /usr/perl/bin use warnings; use strict; my $skip = 0; my $last_line = <DATA>; chomp($last_line); while (my $current_line = <DATA>){ chomp($current_line); if ($current_line =~ /^\d{4}-\d{2}-\d{2}/){ if (not $skip){ print $last_line, qq{\n}; } else{ $skip = 0; } $last_line = $current_line; } else{ print $last_line, qq{ }, $current_line, qq{\n}; $skip = 1; } } print $last_line, qq{\n}; __DATA__ 2013-01-01 user1 user2 chat chat 2013-01-02 user3 user4 more chat more chat 2013-01-03 user5 user6 nazi nazi chat chat nazi 2013-01-04 user 7 user8 see you in the pub
2013-01-01 user1 user2 chat chat 2013-01-02 user3 user4 more chat more chat 2013-01-03 user5 user6 nazi nazi chat chat nazi 2013-01-04 user 7 user8 see you in the pub
Boy, am I rusty. It hurt my head getting that to compile and run. :-)

Updated: Reset the $skip flag.