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how do i reset a filehandle?

by Anonymous Monk
on Jun 01, 2000 at 00:30 UTC ( #15701=perlquestion: print w/replies, xml ) Need Help??

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

Hello, Will someone please tell me how to reset a filehandle to point to the beginning of the file it is reading? I know I can achieve this by opening the file, reading, closing the file, and reopening it, but I want to avoid this if possible. Thanks for your help! -relative newbie in dallas

Replies are listed 'Best First'.
Re: how do i reset a filehandle?
by lhoward (Vicar) on Jun 01, 2000 at 01:00 UTC
    Use the seek command. 
    seek HANDLE,0,0;

    [download]
    you mileage may vary if trying to seek on streams or pipes (like STDIN).
[reply]
[d/l]
      Just to clarify lhoward's answer:
      The second parameter for seek is a position, the third parameter is what the position is relative to:

      0 Relative to the beginning of the file.
      1 Relative to the current position.
      2 Relative to the end of the file.

      So, 

        seek HANDLE,0,0
      means to move to index 0 relative to the beginning of the file.
[reply]
[d/l]
[select]
      Just to clarify lhoward's answer:
      The second parameter for seek is a position, the third parameter is what the position is relative to:

      0 Relative to the beginning of the file.
      1 Relative to the current position.
      2 Relative to the end of the file.

      So, 

        seek HANDLE,0,0
      means to move to index 0 relative to the beginning of the file.
[reply]
[d/l]
[select]
RE: how do i reset a filehandle?
by BigJoe (Curate) on Jun 01, 2000 at 00:50 UTC
    I say that this can be handled many ways. My favorite is to read the whole file into a string/array/hash to then do search and replace and testing of the text. 
    open(INFILE, "infile.txt");
my $filesize = -s INFILE;
read(INFILE, $temp, $filesize);
close(INFILE);

$temp = /(regex here)/;

and your other stuff here

    [download]
[reply]
[d/l]
      This gets really bad when you have to deal with large files. (how much memory do you have?) I would suggest getting out of this habit as soon as possible. As others have mentioned, use seek.
[reply]

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