in reply to Stupidest Prime Number detector ever!!

The problem you are coming across isn't Perl, it's your algorithm. Learning algorithms is great -- and there have been recent discussions on algorithms for Primes (use Super Search to look for "Prime") -- but is that what you want to spend your time on right now?

Given your stated goal of learning about Perl and how to make modules, I'd just go down that path with your current algorithm, and just not test or debug it on large prime_candidates to avoid long times.

If you still want to focus on the algorithm, great; here are a few brief comments on your algorithm:

(Before posting, I see ++choroba beat me to most of those algorithm points. I said some things differently, so I am still posting this.)

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Re^2: Stupidest Prime Number detector ever!!
by Anonymous Monk on Jun 23, 2021 at 20:13 UTC

    Thank you for such a detailed post, but, the only way I have used map is to gather the output in another array, for example:  my @array (1..1000);  my @odds = map { $_ % 2 != 0 } @array; .So I am taking a bit of a time getting used to the way you are doing it in the sample code, but that's my bad. Thanks again

      my @odds = map { $_ % 2 != 0 } @array;

      That's not going to do what you think. Consider the following:-

      johngg@abouriou:~$ perl -Mstrict -Mwarnings -E ' say for map { $_ % 2 != 0 } 0 .. 10;' 1 1 1 1 1

      The alternating blanks and ones are registering the FALSE and TRUE results of the expression in the map, which essentially has a one to one relation between input on the right and output on the left. What you should be using instead is grep which filters input, only passing to the left those items for which the expression is TRUE.

      johngg@abouriou:~$ perl -Mstrict -Mwarnings -E ' say for grep { $_ % 2 != 0 } 0 .. 10;' 1 3 5 7 9

      Note also that you could dispense with the != 0 as the expression $_ % 2 will evaluate to either 0 or 1.

      johngg@abouriou:~$ perl -Mstrict -Mwarnings -E ' say for grep { $_ % 2 } 0 .. 10;' 1 3 5 7 9

      I hope this is helpful.




        I meant  grep and not  map. Truly my bad!!