printing up until a certain line within a file

c has asked for the wisdom of the Perl Monks concerning the following question:

i'm working on printing the content of a file, but only up until a certain point. in my case, its until a line beginning with ## START shows up. my code

#!/usr/bin/perl -wT

use strict;

open(FH, "/testfile");
my @lines = <FH>;
&test;
close(FH);

sub test{
for my $i(@lines) {
  if ($i =~ /^\#\# START/) {
    return;
  } else {
    print $i;
  }
}

}
[download]

this works, but it uses return and needs to be held within a subroutine to work. it seems like there should be a better way to do this, and i just am not crafty enough to come up with it. can someone point out another method that doesnt need nesting within a sub?

humbly -c

Comment on printing up until a certain line within a file Download Code

Replies are listed 'Best First'.
Or from the command line line . . . by Fletch (Bishop) on Oct 25, 2001 at 03:30 UTC
`perl -pe 'exit 0 if /^##START/' foo` [download]	[reply] [d/l]
Re: printing up until a certain line within a file by dvergin (Monsignor) on Oct 25, 2001 at 02:43 UTC
...another method that doesnt need nesting within a sub How about: `#!/usr/bin/perl -w use strict; open(FH, "/testfile"); while (my $line = <FH>) { last if $line =~ /^## START/; print $line; } close(FH);` [download]	[reply] [d/l]
Re: printing up until a certain line within a file by lestrrat (Deacon) on Oct 25, 2001 at 02:31 UTC
Well, how about this: `sub print_up_to { my( $handle, $string ) = @_; while( <$handle> ) { last if /$string/o; print; } } use FileHandle; my $fh = FileHandle->new( 'foo' ); print_up_to( $fh, '^## START' ); ## of course, you should be able to do this: open( FOO, 'foo' ); print_up_to( \*FOO, '^## START' );` [download]	[reply] [d/l]
Re: printing up until a certain line within a file by blackmateria (Chaplain) on Oct 25, 2001 at 02:52 UTC
I think you can do this with the .. operator but I'm not sure if this is the best way. Maybe this will help, though: `#!/usr/bin/perl -w use strict ; if (open (my $file, '/testfile')) { while (<$file>) { print if 1../^## START/ ; } close $file ; }` [download] Update: Oops, forgot to mention, the .. operator is documented in perlop. Thanks c.	[reply] [d/l]
Re: printing up until a certain line within a file by Rex(Wrecks) (Curate) on Oct 25, 2001 at 04:43 UTC
++ for a nice clear question with the right amount of code. And a ++ for the oneliner solution..neat and to the point :) "Nothing is sure but death and taxes" I say combine the two and its death to all taxes!	[reply]


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