1. I put the file inside the script to keep everything together. Another way of doing this would be to place the data at the end of the script after a __END__ or __DATA__ tag and read the DATA filehandle that the interpreter opens for you. However, I wanted to show you how to use the three-argument form of open which is considered best practice these days. Just substitute your variable containing your file to be read for the \ <<EOD ...

2. I just put the line numbers in the data to show that the script was giving the "right" answers. Having them there did not affect how the script ran.

3. Put something like my ( $file, @phrases ) = @ARGV; at the top of your script so that you don't have to worry how many phrases are being sought.

4. If you are calling your script from the command line with a file and a series of phrases then I imagine you will enclose each phrase in single-quotes. To avoid the problem where the phrase might contain regex metacharacters change the line compiling the regex to my $rxPhrase = qr{\Q$phrase\E};

Cheers,

JohnGG

yes John


total cpu sold: 45

i need that 45...
even though that phrase was present before, we shud ignore it and follow the order in which the phrases are passed as arguments.... and return the last phrase's value (ie., 45)


if the last phrase was not found in that file then the last but one phrase, if not found the previous one and so on...

that is why the order in which we search is very important...

if u still have questions, i can explain it to you further down

thanks,
Mercury.

Here you go:

$ cat spw663850.dat
total Laptops produced: 60
total cpu sold: 57
total mice produced: 40
total cpu sold: 45
total Laptops produced: 68
total mice produced: 48
total cpu sold: 51
total printers produced: 19
total monitors produced: 149
$
$
$ cat spw663850
#!/usr/bin/perl
#
use strict;
use warnings;

use List::Util q{first};

my ( $inFile, @phrases ) = @ARGV;
my $lastPhrase = $phrases[ -1 ];

open my $inFH, q{<}, $inFile
   or die qq{open: $inFile: $!\n};
my @lines = <$inFH>;
close $inFH or die qq{close: $!\n};

foreach my $phrase ( @phrases )
{
    my $rxPhrase = qr{\Q$phrase\E};
    my $lineNo =
      first { $lines[ $_ ] =~ $rxPhrase } 0 .. $#lines;

    unless ( defined $lineNo )
    {
        print qq{$phrase: not found in sequence\n};
        next;
    }

    print qq{$1\n}
       if $lines[ $lineNo ] =~ m{\Q$lastPhrase\E\s*(\d+)};

    $lineNo ++;
    splice @lines, 0, $lineNo;
}
$
$
$ ./spw663850 spw663850.dat 'total Lap tops produced:' 'total mice pro
+duced:' 'total cpu sold:'
45
$
[download]

Feel free to ask if the script is not clear. I cleaned up the data file so that none of the lines had spaced before the colons just for consistency.

Cheers,

JohnGG