Question

I got this problem. I don’t know if I’m just too tired or if there is something not working.

My code is:

$sX = ($nr == 1 or $nr == 4 or $nr == 7 ? "0" : ($nr == 2 or $nr == 5 or $nr == 8 ? "200" : "400"));
$sY = ($nr == 1 or $nr == 2 or $nr == 3 ? "0" : ($nr == 4 or $nr == 5 or $nr == 6 ? "200" : "400"));

$nr is an integer in the range [1..9] (it’s in a loop). Just right one row below this statement, I output this two vars. And then both of them are "1" or null. Why? I just can’t see it 🙁

Thanks

Flo

Answer 1

It’s because the ternary operator has a higher operator precedence than logical or. Add parentheses around all of your x or y or z parts. In other words, you might as well have written that expression as:

$sX = ($nr == 1 or $nr == 4 or ($nr == 7 ? "0" : ($nr == 2 or $nr == 5 or ($nr == 8 ? "200" : "400"))));

Same for the second one.

Reference: http://php.net/language.operators.precedence