File Position
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From: mud_saisem on 17 Feb 2010 23:21 Hi There, Does anybody know how to read through a file searching for a word and printing the file position of that word ? Thanks.
From: Tad McClellan on 17 Feb 2010 23:56 mud_saisem <mud_saisem(a)hotmail.com> wrote: > Does anybody know how to read through a file searching for a word and ^^^^^^^^^ > printing the file position of that word ? ----------------------- #!/usr/bin/perl use warnings; use strict; my $pos; while (<DATA>) { if ( /(.*)searching/ ) { print $pos + length $1, "\n"; exit; } $pos += length; } __DATA__ Hi There, Does anybody know how to read through a file searching for a word and printing the file position of that word ? Thanks. ----------------------- -- Tad McClellan email: perl -le "print scalar reverse qq/moc.liamg\100cm.j.dat/"
From: Peter Makholm on 18 Feb 2010 00:22 mud_saisem <mud_saisem(a)hotmail.com> writes: > Does anybody know how to read through a file searching for a word and > printing the file position of that word ? If your file contains plain ascii, iso-8859, or another 8bit charset it should be easy. The tell() function gives you the current location in the file, pos() gives you the location of regexp match, and index() directly gives you the location. So this should work (untested though) my $offset = 0; while (<$fh>) { if (/word/) { say "Found 'word' at location ", $offset + pos(); } $offset = tell $fh; } If you file contains a variable width uniode encoding (like utf-8) it gets a lot harder. //Makholm
From: mud_saisem on 18 Feb 2010 00:50 On Feb 18, 4:22 pm, Peter Makholm <pe...(a)makholm.net> wrote: > mud_saisem <mud_sai...(a)hotmail.com> writes: > > Does anybody know how to read through a file searching for a word and > > printing the file position of that word ? > > If your file contains plain ascii, iso-8859, or another 8bit charset > it should be easy. The tell() function gives you the current location > in the file, pos() gives you the location of regexp match, and > index() directly gives you the location. > > So this should work (untested though) > > my $offset = 0; > while (<$fh>) { > if (/word/) { > say "Found 'word' at location ", $offset + pos(); > } > $offset = tell $fh; > } > > If you file contains a variable width uniode encoding (like utf-8) it > gets a lot harder. > > //Makholm Very Nice, Thank for the help !
From: J�rgen Exner on 18 Feb 2010 00:56
mud_saisem <mud_saisem(a)hotmail.com> wrote: >Does anybody know how to read through a file searching for a word and >printing the file position of that word ? Please define 'position': are you talking about characters or bytes? Just slurp the whole file into a string and then use index() to get the position of the desired word in that string. This is very straight-forward and unless you are dealing with exceptionally large files (GB size) or unusual distribution of your 'word' (almost always very early in the file) probably also faster than any looping line by line or chunk by chunk. jue |