Text file filtering

[surfmonkey]

Hi, probably a dumb question but I'm looking for a simple way to parse a text file that consists of three headers and multiple lines in between for example:

(+Header1)
...
....
(-Header1)

(+Header2)
......
......
......
(-Header2)

(+Header3)
......
......
.....
(-Header3)

I don't want to divide the dataset into three separate files. Anyone got any ideas?

edited: Fri Jun 28 00:13:37 2002 by jeffa - added pre tags

[dimmesdale]

If I understand your question right, something like this may do what you want:

$your_data =~ /\+Header1(.|\n+)-Header1\n\+Header2(.|\n+)-Header2\n\+H
+eader3(.|\n+)-Header3\n/;

I wouldn't suggest using that as anything but a starting point, though. There are regex options for changing the . operator to match \n's, and you may want to consider doing a line by line parse (and having boolean--i.e., flag--variables to tell you what section you're in).

The last suggestion might be started like this:

while ($line = <your_file_handle>) {
  if($line =~ /^\+Header1/) { $header1 = 1; next }
   # if +Header1 has its own line use next
  elsif($line =~ /^-Header1/) { next }
  else { $header1 = 0 }
  .
  .
  .
  if($header1) {
    $h1_data[$index++] = $line;
  }
 .
 .
 .
}

Again, these are just quick things to get you started thinking; you may want to look at this site and search for regex, or look at the perlman pages for more information regarding them.

[surfmonkey]

Thanks, what I want to do is match the block of data between the two headers so that I can put it into a separate variables so that at the end I have three variables containing the data from between the separate headers. I just can't get my head around using regexp's :o(

[bwana147]

IIUC, the headers stand on a line by themselves. Then, you might want to have a look at the flip-flop operator (..).

perldoc perlop

while ( <> ) {
    if ( /\(\+Header1\)/ .. /\(-Header1\)/ ) {
        # you're in part one
    }
    if ( /\(\+Header2\)/ .. /\(-Header2\)/ ) {
        # you're in part two
    }
    if ( /\(\+Header3\)/ .. /\(-Header3\)/ ) {
        # you're in part three
    }
}

HTH

--bwana147