breaking out of outer loops
Chris Angelico
rosuav at gmail.com
Mon Mar 7 18:47:16 EST 2016
On Tue, Mar 8, 2016 at 10:09 AM, Fillmore <fillmore_remove at hotmail.com> wrote:
> For the record, here's a Perl script of mine I'm trying to port...there may
> be 'malformed' lines in a TSV file I'm parsing that are better discarded
> than fixed.
>
> my $ctr = 0;
> OUTER:
> while($line = <FILE>) {
>
> $ctr++;
> if ($ctr < 5) {next;}
>
> my @allVals = split /\t/,$line;
>
> my $newline;
> foreach my $i (0..$#allVals) {
>
> if ($i == 0) {
> if ($allVals[0] =~ /[^[:print:]]/) {next OUTER;}
>
> $newline = $allVals[0];
> }
>
> if (defined $headers{$i}) {
>
> #if column not a number, skip line
> if ($allVals[$i+1] !~ /^\d+$/) {next OUTER;}
>
> $newline .= "\t".$allVals[$i+1];
> }
> }
> print $newline."\n";
>
> }
I'm not too fluent in Perl, but my understanding here is that "next
OUTER" is equivalent to Python's 'continue' statement, right? So your
flow control is roughly this:
for _ in range(5): skip header row
for line in file:
for cell in split(line):
if bad_cell_value:
break # Skip out of the inner loop now
else:
print_stuff # We didn't break
Does that look right? The key here is that a 'for' loop has an 'else'
clause, which happens if there's no 'break' in the main loop. I think
that's what you're after, here; you get to break out of "the loop and
a little bit more", so to speak. The outer loop is actually immaterial
here.
ChrisA
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