Re^2: Learning Perl - Question About Using a For Loop To Pull Data From an Array

Thank you for your reply. As you mentioned the script works fine. This is an example from a textbook which is why it may seem odd and not look like a real world script.

I am not having any issues with the code, rather I am trying to understand how the for loop is using the $counter variable to pull out the actual number that user entered when it appears that $counter is being used as a scalar.

For example if the user enters 1 and 3 they get fred and barnet back which are the first and third items in the array respectively.

What is confusing me is why is $names $counter - 1 giving the correct values back. If the user enters 2 values, such as 1 and 3, $counter would = 2, not 1 or 3 since it is being treated as a scalar. Yet the script correctly returns the 1st and 3rd item in the array instead of the the 1st and 2nd item of the array.

Thank you for your help.

Comment on Re^2: Learning Perl - Question About Using a For Loop To Pull Data From an Array

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Re^3: Learning Perl - Question About Using a For Loop To Pull Data From an Array by NetWallah (Canon) on Apr 01, 2016 at 18:44 UTC
It seems that the name chosen, $counter, is confusing you. It is being used as an INDEX, rather than as a traditional COUNTER. The array is indexed from 0 to (n-1). (Updated to n-1)(Thanks, Corion) You need to subtract one from the value entered, in order to get the equivalent index for a zero-based array. Hopefully, that clarifies things. FYI, Fred's friend is named Barney, not barnet. and Barney's kid is Bamm-Bamm. This is not an optical illusion, it just looks like one.	[reply]
Re^3: Learning Perl - Question About Using a For Loop To Pull Data From an Array by Marshall (Canon) on Apr 01, 2016 at 20:33 UTC
What this `foreach $counter (@userNumber){}` does is assign $counter to each value in the array @userNumber. It does this on a first in, first out basis. If the user entered say 1,3,2.. The first loop $counter = 1, then $counter =3, then on last loop, $counter = 2. Before `print "\nthe name is: $names[$counter - 1]`, add a statement, `print "counter = $counter\n";`. And you can see what counter is. Use some non-sequential test cases. Part of the problem here is a rather poor choice of names for "counter". $name_number or something similar would have been better. There is no "count" function of $counter! It is being used as a 1 based index to the names array. Perl starts arrays at 0, not one, so that is what $counter-1 is all about. Hopefully that makes sense?	[reply] [d/l] [select]