This is a pretty simple thing to do. Say you have a list of your grades for the semester. As you take your tests and whatnot, you want to create a new list showing your grades up to a certain point. Here is how you would do so:

#!/usr/bin/perl

@FirstMonth=('A ','B ','A ','D ');

@SecondMonth=('A ','B ','C ','A ',@FirstMonth);

print @SecondMonth;

This adds the values in @FirstMonth to the end of the @SecondMonth list, resulting in:

  A B C A A B A D

We could continue this process as the months go on:

#!/usr/bin/perl

@FirstMonth=('A ','B ','A ','D ');

@SecondMonth=('A ','B ','C ','A ',@FirstMonth);

@ThirdMonth=('F ','F ','A ','A ',@SecondMonth);

@FourthMonth=('A ','A ','A ','A ',@ThirdMonth);

print @FourthMonth;

You will note that I did not write @FourthMonth=('A','A','A','A',@FirstMonth,@SecondMonth,@ThirdMonth). This is because it would have been redundant and added even more fields. Remember that the @SecondMonth already contains all of @FirstMonth's value. And likewise, @ThirdMonth contains all of @FirstMonth and @SecondMonth's values. And so forth.

The result of this code is:

  A A A A F F A A A B C A A B A D

And while we are at it, we can also assign variables to the mix as well. Here it is in code:

#!/usr/bin/perl

@FirstMonth=('A ','B ','A ','D ');

@SecondMonth=('A ','B ','C ','A ',@FirstMonth);

@ThirdMonth=('F ','F ','A ','A ',@SecondMonth);

@FourthMonth=('A ','A ','A ','A ',@ThirdMonth);

$ExtraCredit="A";

@Total=(@FourthMonth, $ExtraCredit);

print @Total;

The end result:

  A A A A F F A A A B C A A B A D A

Looks like you had some extra-curricular activity in their a few times with those F's. Wink, wink.

Well, that's all the time we have for this one. We still have a ways to go on Lists and Hashes, including Multi-Dimensional lists and the List::Util, but we're making progress. Be sure to join me next time as we continue, and hopefully one day, finish this discussion.

Till then...