So, to expand on [id://japhy]'s answer, your 'while($value => 10)' phrase would be equivalent to while($value , "10"). It would always been 'true', so the loop would never terminate. The two terms you used, '=>' and '>=', are not equivalent in Perl. Order is imporant. 'House cat' is not the same as 'cat house'. Check out perldoc perlop for details.