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Re: Cannot find the error (updated)

by AnomalousMonk (Bishop)
on Apr 03, 2020 at 18:51 UTC ( #11115002=note: print w/replies, xml ) Need Help??

in reply to Cannot find the error

Another way. I've "corrected" all the presumably incorrect  't13:45\n' lines to  "t13:45\n" (single-quotes to double quotes so the  \n escape means something) and added a blank line to section output for looks.

use strict; use warnings; my @lines = ( "t13:45\n", "D13:45\n", "S13:45 Unicorn\n", "D13:45\n", "S13:45\n" +, "T13:45\n", "t13:45\n", "D13:45\n", "T13:46\n", "t13:45\n", "D13:45\n", "S13:45\n","D13:45\n", "S13:45 UNICORN\n", + "T13:45\n", "t13:45\n", "D13:45\n", "T13:46\n", ); use constant GOOD_LINE => qr{ \A [tTJSD] }xms; use constant END_SECTION => qr{ \A T }xms; my $value = "uNiCoRn"; my @section; LINE: while (my $line = shift @lines) { die "bad line '$line'" unless $line =~ GOOD_LINE; push @section, $line; next LINE unless $line =~ END_SECTION; if (grep m{ (?i) \Q$value\E }xms, @section) { print for @section; print "\n"; } @section = (); } __END__ t13:45 D13:45 S13:45 Unicorn D13:45 S13:45 T13:45 t13:45 D13:45 S13:45 D13:45 S13:45 UNICORN T13:45
The grep in the section-printing conditional at the end of the loop is a little wasteful because it will continue matching after a match is found. See List::Util::any() for an alternative that may be better (because it short-circuits) if the number of lines in a section is very large or matching is very expensive.

Update: It occurs to me that you may want a strict ordering of section markers so that a  't...' line only occurs at the start of a section. If that's the case, define a section start regex
    use constant START_SECTION => qr{ \A t }xms;
and add this die statement
    die "start line '$line' not at start of section"
        if $line =~ START_SECTION and @section;
just before the
    push @section, $line;
statement. That oughta fix it. (Update: And if you want a really strict strict ordering, let me know; can do, will do.)

Give a man a fish:  <%-{-{-{-<

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