http://www.perlmonks.org?node_id=143755

This short script displays the prime numbers found in a range given by the user.
How it works: The user inputs the range $o to $e. A for command checks every number from $o to $e. For each number that evenly goest into the tested number ( if($i % $j==0) ), the script adds the factor ($j) into an array (@prime) at the $p position. $p starts at zero, and increases by 1 with every factor placed in @prime. If the second position of @prime is equal to the tested number, the tested number is prime.
#! Perl print "Find primes from: "; $o = <>; print "to: "; $e = <>; for($i=$o; $i<=$e; $i++){ $p=0; for($j=1; $j<=$i; $j++){ if($i % $j==0){ $prime_[$p] = "$j"; $p++; } if ($prime_[1] == $i){ print "$i is prime"; print "\n"; } } }