Arrays and the foreach loop hw2

In this homework we are going to do some simple changes to a perl program, like we did during the last lab session. If you have Linux on your laptop you can download the program and change it with a text editor like we did in the lab. Note that your Linux may be a little different, so you may need to looks for the Terminal and the Text Editor, but they are there somewhere. If you do not have Linux yet, you can use codepad. This task is coded “hw2“.

We have seen that a variable $variabile is like a box where we can put values (numbers or strings). An array @array is like many boxes, or a box with many boxes inside, each one having a numeric index 0 to $#array. The easiest way to do something on the content of each box in the array is the foreach loop.

Consider the following script:

@numeri = (3,66,2,34,12,57);
$lunghezza = 0;

foreach $i (@numeri) {
    $lunghezza++;
    print "$i\n";
}

print "Lunghezza dell'array: $lunghezza\n";

As we did in the last lab, here is a list of changes that you have to make to the program. After you do one, run the program and check that the output is correct. Do not try to do them all together or you will die and burn in hell. OK, maybe not that, but we can assure you it won’t be pretty. Here are the changes:

1. compute and print the sum of the numbers in the array,
2. compute and print the arithmetic mean of the numbers in the array,
3. compute and print the maximum number in the array,
4. instead of computing the length of the array like we did, use the $#numeri special variable

You can easily check if you are doing things right. You will need to add other variables, print statements and stuff. For change 3 you will probably need to add an if. Feel free to peruse the slides, copy pieces from old programs, google things, etc. Try to do things by yourself before asking other people, it is the only way to learn. It is fine to compare your work with those of others (we recommend you do) but you should do your own first. If you can not do it, ask for help, but think about it with your head, otherwise it is useless.

You can ask your questions in the comments to this post, so everybody can see the answer. Let us know if you find the homeworks too hard! (or too easy 😉

How to submit your work

Once you checked that your script is okay, you must submit the work done filling this form. Remember to put your login ID, and the correct homework ID (this is hw2, okay?). In this case you can just put the final script on the first box (perl script 01).
In the future you might be required to produce more than one script.