while nested in foreach

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

I have a while loop for a data file that is nested in a foreach loop (to look at 2 data files). My next statements inside the while loop are not working at all. They seem to be doing the next on the foreach instead of the while. Is there a way around this? I'm looking at raw test data and trying to skip data before 5pm the previous day and after 5pm of the current day. The substr is where the hour is located on the data line.

$day_counter = 0;
foreach $dat_file ( @dat_file ) {
        open RAW, "<$dat_file";
        while ( <RAW> ) {
                next (($day_counter == 0)&&(substr($_,9,2)<17));
                next (($day_counter == 1)&&(substr($_,9,2)>16));
                ($sum,$error) = 0;
                @numbers = split( '\t', $_ );
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Re: while nested in foreach by Abigail-II (Bishop) on Dec 01, 2003 at 14:25 UTC
If I run this, I get: `Label not found for "next " at /tmp/next line 9, <RAW> line 1.` [download] which doesn't quite surprise me. Are you sure you don't want an 'if' between the 'next' and the condition? Abigail	[reply] [d/l]
Re: Re: while nested in foreach by ear (Acolyte) on Dec 01, 2003 at 14:28 UTC
Teach me to skip that second cup of coffee. I've been playing with this for 30 mins trying to figure out why it was only looking at the first line of data then stopping. I was sure it was doing the next on the filename istead of the raw data. Ugh. Thanks much, that of course fixed the problem.	[reply]
Re: while nested in foreach by AcidHawk (Vicar) on Dec 01, 2003 at 14:29 UTC
From your description it seems as if you need an `if` between the `next` and the `(($day...` Something like `next if (($day_counter == 0)&&(substr($_,9,2)<17)); next if (($day_counter == 1)&&(substr($_,9,2)>16));` [download] Update: D'oh Abigail-II was much faster with his reply. ----- Of all the things I've lost in my life, its my mind I miss the most.	[reply] [d/l] [select]
Re: while nested in foreach ($_ pitfalls) by Russ (Deacon) on Dec 01, 2003 at 17:54 UTC
When I read the subject ("while nested in foreach"), I thought this would be a different problem. Just for grins, here is a "gotcha" to watch for: resetting $_. `for (1..10){ print "Before nested \$_ setter: $_\n"; open JUNK, 'junk' or die "Nope: $!"; while(<JUNK>){ # Do nothing, just let $_ get set } close JUNK; print "After nested \$_ setter: $_\n"; }` [download] In this example (perl 5.8.0), the second print statement shows an empty $_ because the diamond operator (in the while loop) overwrote $_ (as we told it to do). So, after the nested while loop, we no longer have the old value in $_ (the counter in the for loop). Exercises left for the reader: replace the while loop with other $_-using constructs and see how they behave... Most perl built-ins, and many CPAN modules, are "smart" enough to localize $_ to prevent confusion, but not all. Russ	[reply] [d/l]