Hi BrowserUk,

Thanks for your helpful response! I've created the index as you indicated above in your code, using this:
open(IN, $oneper) or die "Can't open file $oneper for reading: $!\n";
open(INDEX, ">:raw","$file.idx") or die "Can't open $file.idx for read
+/write: $!\n";

syswrite INDEX, pack('N',0),4;
while (<IN>) {
syswrite INDEX, pack('N', tell INDEX), 4;
}
close INDEX;

[download]

I've created a file to read, as follows:
open INDEX, "<:raw","$index" or die "Can't open $index for reading: $!
+";
my $len = -s( INDEX );
sysread INDEX, my( $idx ), $len;
close INDEX;

open FILE, "<$oneper" or die "Can't open $oneper for reading: $!";

foreach my $lineNum (sort {$a cmp $b} keys %todo) {
  my $offset = unpack 'N', substr $idx, $lineNum * 4, 4;
  print "offset is $offset for linenum $lineNum\n<br>";
  seek FILE, $offset, 0;
  my $line = <FILE>;
  print "found line $line\n";
}

[download]

The start of my file is:
1       NoResults
2       NoResults
3       13      32446841        0
4       13      32447221        0
5       7       91839109        1
6       7       91747130        1
7       7       91779556        1
8       7       92408328        0
9       7       92373453        0
10      7       92383887        0
11      7       11364200        0
12      7       11337163        0

When I supply lineNum 3 it gives me back:
offset is 12 for linenum 3
found line 2 NoResults

What have I done wrong? :( It feels like it's not indexing an entire line?

In reply to Re^2: Index a file with pack for fast access by Ineffectual
in thread Index a file with pack for fast access by Ineffectual

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