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

Hello,

I have this code: 

#!c:\perl\bin\perl.exe

use strict;
use warnings FATAL => 'all';
use Fcntl qw[:flock];

my $impressions = 0;
my $FH = 'C:\\scripts\\20040120\\mr\\imp\\';

chdir $FH or die "$!";

while (glob '*Jan2004*.txt') {
    open FH, $_ or die $!;
    flock FH, LOCK_SH or die $!;
    while (<FH> ) {
        chomp;
        if ( /Impressions:/ ) {
        my($text, $value) = split(/:/, $_);
        print "Impressions: $value";
        print "\n"
        #$impressions += $value;
     }
    }
    close FH or die $!;
  }

print 'Total impressions: ', $impressions or die $!;<br>

[download]
This code opens file and retrieves a value assigned to 'Impressions:' I would like to caunt all values. The output so far looks like this: 
C:\scripts\20040120\mr>perl c07_impressions_i.pl
Impressions:                    85
Impressions:                    19298
Impressions:                    n/a
Impressions:                    25082
Impressions:                    8314
Impressions:                    8663
Impressions:                    8672
Impressions:                    8078
Impressions:                    n/a
Impressions:                    26167
Impressions:                    7708
Impressions:                    8247
Impressions:                    14070
Impressions:                    9641
Impressions:                    n/a
Total impressions: 0
C:\scripts\20040120\mr>

[download]
Because there are 'n/a' I cant count the impressions together. How should I change the script so it will replace any occurence of 'n/a' with 0 (zero)?

Thank you for your time.
danield

update (broquaint): tidied up formatting

Replies are listed 'Best First'.
Re: How to substitute 0 (zero) Instead of 'n/a'
by arden (Curate) on Jan 22, 2004 at 18:41 UTC
    Use an "if digit" statement, like this:

    $impressions += $value if ( $value =~ /\d+/ );

    where you have #$impressions += $value;

    Of course, you might also want to put in the semi-colon on the print line above it, or just add the newline character to the previous print statement... :)

[reply]
[d/l]
[select]
Re: How to substitute 0 (zero) Instead of 'n/a'
by Zed_Lopez (Chaplain) on Jan 22, 2004 at 18:55 UTC

    Well, there are a bazillion ways to do this.

    $impressions += $value unless $value =~ m{n/a};

    [download]

    is one obvious way.

    I'd be more inclined toward

    while (<FH>) {
  if (/Impressions:/) {
    print;
    $impressions += $1 if /(\d+)/;
  }
}

    [download]
[reply]
[d/l]
[select]
Re: How to substitute 0 (zero) Instead of 'n/a'
by duff (Parson) on Jan 22, 2004 at 19:12 UTC

    One simple way is to force perl to treat $value like a number. Since it's the string "n/a", treating it like a number will evaluate to 0. To force perl to treat it like a number, do something numeric with it. For instance:

       while (<FH> ) {
       chomp;
       if ( /Impressions:/ ) {
       my($text, $value) = split(/:/, $_);
       print "Impressions: $value";
       print "\n"
       $value += 0;                 # turn $value into a number
       $impressions += $value;
    }

    [download]

    HOWEVER, you're already treating $value like a number when you add it to $impressions, so if you uncomment that line it should just work without the added step of adding 0 to $value

    duff

[reply]
[d/l]
[select]
      If you must do this, try like this instead: 
      use warnings;
while (<FH> ) {
    chomp;
    if ( /Impressions:/ ) {
       my($text, $value) = split(/:/, $_);
       print "Impressions: $value";
       print "\n";
       {
          no warnings "numeric";
          $value += 0;                 # turn $value into a number
       }
       $impressions += $value;
    }
}

      [download]
[reply]
[d/l]
Re: How to substitute 0 (zero) Instead of 'n/a'
by toonski (Beadle) on Jan 22, 2004 at 18:43 UTC
    Kind of a hack solution, but try running this script: 
    #!c:\perl\bin\perl.exe

use strict;
use warnings FATAL => 'all';
use Fcntl qw[:flock];

my $FH = 'C:\\scripts\\20040120\\mr\\imp\\';
chdir $FH or die "$!";

while (glob '*Jan2004*.txt') {
    open FH, $_ or die $!;
    flock FH, LOCK_SH or die $!;
    while (<FH> ) {s/n\/a//}
    close FH or die $!;
}

print 'replacing completed'

    [download]
    untested, but theoretically, that oughta work :)
[reply]
[d/l]
      I don't think danield is wanting to replace the data in the files with zeros, just not allow the 'n/a's screw up his count. I could be wrong, in which case your solution works... :)
[reply]

Back to Seekers of Perl Wisdom