in reply to Writing files

How do you know which lines you want? It is because of the line's contents? Or because of the lines position (i.e. line number)?

If you are trying to find a line by line-number and and you have fixed-length lines (all lines are the same length). Then you could seek to move to the correct location in the file and then read in the data. If the lines are not fixed-length then you will have to examine every line, counting line numbers and just not processing the ones you don't care about.

If you are trying to extract lines based on their contents, then you will have to examine each line in the file. In order to determine if you are interested in it.

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RE: Re: Writing files
by Anonymous Monk on Jul 28, 2000 at 21:55 UTC
    I think it would be better if I examine all the lines and get the one I wanted. But they are all differeent. But how? Thankx
[reply]
      two words: regular expressions.
      two more words: not necessarily. 
      open FILE, "file.txt" or die "can't do : $!\n";
while (<FILE>)
{
   # do some test on $_
   # if it's a string you want, keep it
}
close FILE;

      [download]
      those tests are most likely going to be some sort of regular expression. but it depends on what you are looking for. what lines do you want to keep? how do you know you want to keep them?
[reply]
[d/l]

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