> ----Original Message-----
> From: Umesh T G [mailto:[EMAIL PROTECTED]
>
> Sent: Friday, July 29, 2005 3:47 PM
> To: beginners@perl.org
> Subject: Read a single line in a file.
>
>
> Hello List,
>
> I have a file with multiple lines. I want to read only the first line.
>
> and a particular word in that line.
>
>
> For eg:
>
> File.txt
>
> apple,grape,orange,banana
> some other lines
> continued.
>
> So I want only the word grape here. How to get it?
>
>From the cookbook, recipe 8.8 "Reading a Particular Line in a File"
I use it and it works good. With this you can select any single line number,
not
just the first. You should be able to figure out how to extract a particular
word from the line
----
# usage: build_index(*DATA_HANDLE, *INDEX_HANDLE)
sub build_index {
my $data_file = shift;
my $index_file = shift;
my $offset = 0;
while (<$data_file>) {
print $index_file pack("N", $offset);
$offset = tell($data_file);
}
}
# usage: line_with_index(*DATA_HANDLE, *INDEX_HANDLE, $LINE_NUMBER)
# returns line or undef if LINE_NUMBER was out of range
sub line_with_index {
my $data_file = shift;
my $index_file = shift;
my $line_number = shift;
my $size; # size of an index entry
my $i_offset; # offset into the index of the entry
my $entry; # index entry
my $d_offset; # offset into the data file
$size = length(pack("N", 0));
$i_offset = $size * ($line_number-1);
seek($index_file, $i_offset, 0) or return;
read($index_file, $entry, $size);
$d_offset = unpack("N", $entry);
seek($data_file, $d_offset, 0);
return scalar(<$data_file>);
}
# usage:
open(FILE, "< $file") or die "Can't open $file for reading: $!\n";
open(INDEX, "+>$file.idx")
or die "Can't open $file.idx for read/write: $!\n";
build_index(*FILE, *INDEX);
$line = line_with_index(*FILE, *INDEX, $seeking);
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