Question

So here are the

$y = 0 | 2 | 4;  # answer is  6

$x = 0 || 2 || 4;  # answer is 2

I know why $y is 6 because it’s using the OR operator on each number and 2 | 4 = 6 but for $x…

Why is it 2?

Answer 1

Because 2 is the first non-falsy item and a logical OR short circuits. It evaluates zero which is false, then 2 which is not false so it is done and returns 2. Consider the output of the following example:

$val = 1;
sub a_proc {
    print "a_proc: ", $val++, "\n";
    1;
}
$another_val = &a_proc || &a_proc;

This will output a_proc: 1. As soon as a_proc returns a true value, the interpreter can stop evaluating since a logical OR of true and any value is true.