Looping through end of file once a match is found

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

Hello, I've searched high and low for the answer to my problem, but I've yet to see an example that addresses what I am trying to do. I am hoping that you can help.. Basically, I am reading in a file that in filled with multiple-line log entries. The first line of each log entry has the date (amongst other items) in it in the mm/dd/yyyy format. This Perl script is launched via a web form when a person provides the date that they'd like to search through the logs for (via a dropdown menu on the webpage). If the date that the user requests matches the date in the logfile, it should print everything from that first matching line until the very end of the file. The log is set up in such a manner that the day that the person is requesting will always be the latter portion of the file. With this in mind, here's the code block in question:

LINE: while ($currentfile=<FILE>) {
      if ($currentfile =~ /^[0-9][0-9][0-9][0-9][0-9][0-9]/){
        $match_date = substr($currentfile,52,10);
        if ($search_date eq $match_date) {
            print RESULTS "$currentfile";
            do {
                next LINE;
                print RESULTS "$currentfile";
            } until eof();
          }  #if search_date
        } # if $currentfile
  }
}
[download]

One other note, the reason that I am trying to match on that particular reg ex is because the first line of each log entry (which also includes the date in mm/dd/yyyy format) begins with a six digit sequence number (with leading zeroes). Thanks very much in advance for any guidance!

Comment on Looping through end of file once a match is found Download Code

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Re: Looping through end of file once a match is found by Animator (Hermit) on Jun 21, 2005 at 16:37 UTC
My guess is that you do not know what exactly next does. Here is the basic idea: it stops the execution of the current block with the current item, and start all over again with the next item. In your code the following two lines will never be executed: `print RESULTS "$currentfile"; } until eof();` [download] My guess is that you think it will store the next entry in `$currentfile` and continue right after the `next LINE`. This is not the case. You could replace the `do { } until` block with another `while (<FILE>) { }` or you can go with the suggestion other have already made. (Which are better!)	[reply] [d/l] [select]
Re: Looping through end of file once a match is found by davidrw (Prior) on Jun 21, 2005 at 16:20 UTC
I believe you can simply replace: `do { next LINE; print RESULTS "$currentfile"; } until eof();` [download] With `print RESULTS <FILE>;` because `<FILE>` will be treated in array context there and grab everything. After that, execution will fall through naturally and when it tries `while ($currentfile=<FILE>) {` again, it will be at eof so will break out of that loop. Another approach (basically set a flag for when outputting is ok: `my $matchFound = 0; while ($currentfile=<FILE>) { if( ! $matchFound ){ $matchFound = 1 if $currentfile =~ /^\d{6}/ && $search_date eq sub +str($currentfile,52,10); } next unless $matchFound; print RESULTS $currentfile; }` [download] And yet another way (take advantage of split), though this involves slurping the log which might be bad if it's large (very untested): `my $currentfile = do { local $/ = undef; <FILE> }; my @parts = split /(^\d{6}).{46}$search_date)/m, $s, 2; print RESULTS @parts[1,2] if $parts[1];` [download]	[reply] [d/l] [select]
Re: Looping through end of file once a match is found by Transient (Hermit) on Jun 21, 2005 at 16:16 UTC
`my $found_date = 0; LINE: while ($currentfile=<FILE>) { if (!$found_date and $currentfile =~ /^\d{6}/){ $match_date = substr($currentfile,52,10); if ($search_date eq $match_date) { $found_date = 1; } } next unless $found_date; print RESULTS "$currentfile"; }` [download]	[reply] [d/l]
Re^2: Looping through end of file once a match is found by thundergnat (Deacon) on Jun 21, 2005 at 16:18 UTC
`while ($currentfile = <FILE>) { if ($currentfile =~ /^\d{6}/ and $search_date eq substr($currentfi +le,52,10) { print RESULTS $currentfile; print RESULTS while <FILE>; } }` [download] Oops. This was supposed to be a reply to the OP, not Transient.	[reply] [d/l]
Re: Looping through end of file once a match is found by mkmcconn (Chaplain) on Jun 21, 2005 at 19:47 UTC
Would you be looking for something as simple as this ? `# when $search_date is found beginning in the 52nd column # of a log entry that begins with 6 digits, then # print the matching line and the remainder of the file. my $gate = ''; for(<FILE>){ if ( $gate \|\| ($gate = /^\d{6}.{45}$search_date/)){ print RESULT; } }` [download] mkmcconn	[reply] [d/l]
Re: Looping through end of file once a match is found by GrandFather (Saint) on Jun 21, 2005 at 21:14 UTC
There being more than one way to do it: Read more... Code (748 Bytes) Perl is Huffman encoded by design.	[reply] [d/l]