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

I've got a program that uses an array of hashes to store start and stop times for various jobs. For readability and convenience, I'd like to use a reference in the loop that steps through the array -- something like this: 
foreach my $job (@jobTimes)
{
    $job{'startX'} = int(($job{'start'} - $dayStart) * $scaleConst);
    $job{'endX'} =   int(($job{'end'} - $dayStart) * $scaleConst);
    $job{'start'} =~ s/^0+//;
    $job{'end'} =~ s/^0+//;
}

[download]

Update: tedrek's suggestions worked when initializing the hash, but it's still erroring out when I try to work on it, as listed above. This is where I'd really like to avoid the $jobTimes$i{'foo'} construct.

Thanks,
Alex

Replies are listed 'Best First'.
Re: Reference to a single array item in an array of hashes?
by Ovid (Cardinal) on Apr 05, 2004 at 22:25 UTC

    Why use the extra variable?

    for my $i (0 .. $numTimes) {
    $jobTimes[$i] = {
         start => param("JobStart$i"),
         stop  => param("JobStop$i"),
    };
}

    [download]

    Cheers,
    Ovid

    New address of my CGI Course.

[reply]
[d/l]
      Because then I end up with really ugly stuff like this: 
      $jobTimes[$i]{'startX'} = int(($jobTimes[$i]{'start'} - $dayStart) * $
+scaleConst);

      [download]
      When I would much rather have: 
      $$job{'startX'} = int(($$job{'start'} - $dayStart) * $scaleConst);

      [download]
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[d/l]
[select]
Re: Reference to a single array item in an array of hashes?
by ccn (Vicar) on Apr 05, 2004 at 22:41 UTC
    you can use ref function to determine if an element is reference to hash or something else
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[d/l]
Re: Reference to a single array item in an array of hashes?
by tedrek (Pilgrim) on Apr 05, 2004 at 22:48 UTC

    You can just use the built in aliasing of for loops, (I'm assuming this loop is initializing the array):

    #!/usr/bin/perl
use strict;
use warnings;

my $numTimes = 2;
my $i = 0;
my @jobTimes = ('') x $numTimes; # Make the array big enough

foreach my $job (@jobTimes)
{
    $job = {
        start => param("JobStart$i"),
    };
    $i++;
}

    [download]

    Update: made it compile and do what I mean.

    I tried to swear at perl and it compiled!
[reply]
[d/l]
      Using that code gives an error "Global symbol "$job" requires explicit package name".

      I tried changing it to this:

      foreach my %job (@jobTimes)

      [download]
      but it didn't like that either. Syntax error.
[reply]
[d/l]

        I fixed a few things. But you shouldn't be getting that error unless you are trying to use $job outside of the loop.

        I tried to swear at perl and it compiled!
[reply]
[d/l]

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