Search and replace

funz has asked for the wisdom of the Perl Monks concerning the following question:

I have a flat file with a list of element, they are seperated by a new line (\n) and each line is also seperated by a &, example "4&1028x768". The code below works, it searches the file, when it finds a match (1028x768) it increments the count, deletes the original and adds the updated count at the end of the file. What I need to do is, if it doesn't find a match then it will add a new entry at the end of the file, ex. 1&800x600.

    open (DATA,"$resolution");
    @data = <DATA>;
    close(DATA);

    $data = "@data";

    $data=~ m/.*&$FORM{'res'}\n/i;

    ($count, $res) = split(/&/, $&);

    @add = grep{ !(/.*&$res\n/i) } @data;


    $count++;
    push(@add, "$count&$res\n");

    open (DATA,">$resolution");
    print DATA @add;
    close(DATA);
[download]

Comment on Search and replace Download Code

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Re: Search and replace by atcroft (Abbot) on Jun 14, 2004 at 04:33 UTC
This seems like a good place to use a hash. If I am understanding you properly, your data format is: count&key count&key In such a case, it seems as if you would want to read each line, loading them into a hash, then write them back out. Something along the following lines might work, in such a case: my (%dhash); # Lines assumed to be in @data, adapted from OP's code. open(DATA, $resolution) or die("Can't open $resolution for input: $!\n"); while (my $line = <DATA>) { my @parts = split(/&/, $line); if (exists($dhash{$parts[1]})) { $dhash{$parts[1]} += $parts[0]; } else { $dhash{$parts[1]} = 1; } } close(DATA); # Sample dump routine. open(DATA, '> ' . $resolution) or die("Can't open $resolution for output: $!\n"); foreach my $k (sort(keys(%dhash))) { printf DATA "%d&%s\n", $dhash{$k}, $k; } close(DATA); [download] Hope that helps...	[reply] [d/l]
Re^2: Search and replace by funz (Initiate) on Jun 14, 2004 at 06:18 UTC
Im looking for something more simpler than that, since I expect it to be executing every few seconds.	[reply]
Re^3: Search and replace by BUU (Prior) on Jun 14, 2004 at 06:53 UTC
Have you tried it? Do you know how fast it runs? Do you know how fast it has to be? Simplicity rarely has much to do with speed.	[reply]