Re: how to read multiple lines from a file

One approach is to use the core module Tie::File. For example, if you have an input file “data.txt” containing:

the
quick
brown
fox
jumped
over
the
unfortunate
dog
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Then this script:

#! perl
use strict;
use warnings;
use Tie::File;

my $filename = 'data.txt';
tie my @lines, 'Tie::File', $filename or die "Cannot tie file '$filena
+me': $!";
chomp(my @text = @lines[3 .. 5]);
print "\n", join(' ', @text), "\n";
untie @lines;
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will produce this output:

13:01 >perl 605_SoPW.pl

fox jumped over

13:06 >
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Hope that helps,

Athanasius <°(((>< contra mundum Iustus alius egestas vitae, eros Piratica,

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Re^2: how to read multiple lines from a file
by skyworld_chen (Acolyte) on Apr 13, 2013 at 05:05 UTC

thanks Athanasus. The way you provide is good, but if I want to search a special word across several lines within a file, for example, if a line contains a word "one" and the line next to it contains a word "two", this "tie" seems not as good as I expect. anyway, thanks for your idea

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Re^3: how to read multiple lines from a file

by Athanasius (Archbishop) on Apr 13, 2013 at 06:08 UTC

Hello skyworld_chen,

The solutions by 2teez and TJPride below are good ones, but if you want to adapt my Tie::File approach, just use a sliding window:

#! perl
use strict;
use warnings;
use Tie::File;

my $filename = 'data.txt';
tie my @lines, 'Tie::File', $filename or die "Cannot tie file '$filena
+me': $!";

my @search_words = ('jumped', 'over');

for (0 .. $#lines - 1)
{
    if ($lines[$_    ] =~ /$search_words[0]/ &&
        $lines[$_ + 1] =~ /$search_words[1]/)
    {
        print "\nFound '$search_words[0]' on line ", ($_ + 1),
                ", and '$search_words[1]' on line ", ($_ + 2), "\n";
        last;
    }
}

untie @lines;
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Output:

16:02 >perl 605_SoPW.pl

Found 'jumped' on line 5, and 'over' on line 6

16:03 >perl 605_SoPW.pl
[download]

Your precise requirements are not clear (to me), but this technique can be easily adapted as needed.

Hope that helps,

Athanasius <°(((>< contra mundum Iustus alius egestas vitae, eros Piratica,

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