Hello,

I'm reading from a ini-file which lessons and units are available. This information I store in the hash %available_data. The relevant information for me are the keys. The values I set to undef because I'm not interested in.

The following code snippet shows an example how the hash %available_data could look like.

    my $unit;
    my $lesson;

    $available_data{'02'}{'03'} = undef;
    $available_data{'02'}{'05'} = undef;
    $available_data{'02'}{'11'} = undef;
    
    $available_data{'05'}{'02'} = undef;
    $available_data{'05'}{'03'} = undef;
    
    $available_data{'07'}{'01'} = undef;
    $available_data{'07'}{'04'} = undef;
    $available_data{'07'}{'07'} = undef;
    $available_data{'07'}{'08'} = undef;    

    foreach $unit (sort keys %available_data)
    {
        print "Unit " . $unit . " consists of lessons: ";
        foreach $lesson (sort keys %{$available_data{$unit}})
        {
            print $lesson . " ";
        }
        print "\n";
    }

[download]
The printed result looks like this: 
Unit 02 consists of lessons: 03 05 11 
Unit 05 consists of lessons: 02 03 
Unit 07 consists of lessons: 01 04 07 08

[download]

As you can see I can easily print out which units and lessons are available.

But now I have the following problem: The program is in a specific lesson defined by $unit and $lesson. How do I come to the next lesson.

Examples:
Unit 2, Lesson 11 --> Unit 5, Lesson 2
Unit 5, Lesson 2 --> Unit 5, Lesson 3
Unit 5, Lesson 3 --> Unit 7, Lesson 1

Sorry for this newbie question. But I don't get it.

Thanks for your help

Dirk

In reply to Navigating in hash of hash by Dirk80

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