#30825 [Opn->Bgs]: Ternary operator (?:) goes wrong

ID: 30825 Updated by: derick@php.net Reported By: Arne dot Heizmann at csr dot com -Status: Open +Status: Bogus Bug Type: Unknown/Other Function Operating System: Windows XP PHP Version: 4.3.9 New Comment: There is no way we can change this as other people rely on this. This is also expected behavior. Previous Comments: ------------------------------------------------------------------------ [2004-11-18 16:15:21] Arne dot Heizmann at csr dot com Sorry for the comment spam, but here's another reason why the way it currently works is less useful. Suppose you actually *did* want this: echo (a() ? b() : c()) ? d() : e(); Since humans don't tend to think this way, you would be more likely to write this as: echo (a() && b()) || (!a() && c()) ? d() : e(); and this would be more readable and understandable anyway. ------------------------------------------------------------------------ [2004-11-18 16:08:57] Arne dot Heizmann at csr dot com Ah... thanks for your comment, tony2001@php.net. I think it should work the other way than it does because it is more useful. Situations in which you want to use the result of a conditional ?: operation as the condition in other ?: operation are extremely rare. It is much more likely that you want to go through a set of cases, such as: $result = $var == 1 ? 'Result 1' : $var == 2 ? 'Result 2' : $var == 3 ? 'Result 3' : $var == 4 ? 'Result 4' : ''; According to the way the operator currently works, this requires a heck of a lot of parentheses: $result = $var == 1 ? 'Result 1' : ($var == 2 ? 'Result 2' : ($var == 3 ? 'Result 3' : ($var == 4 ? 'Result 4' : ''))); which I think is pretty ugly. ------------------------------------------------------------------------ [2004-11-18 16:05:49] Arne dot Heizmann at csr dot com I understand now that the test case outputs "No" because it interprets the code as: echo (true ? "Yes" : false) ? "No" : "No2"; but clearly this is not useful; I think the precedence of the operator should be changed so that programmers won't have to insert extra parentheses to disambiguate the construct. ------------------------------------------------------------------------ [2004-11-18 16:03:32] tony2001@php.net Could tell me how do you think it should work: like this echo (true ? "Yes" : false) ? "No" : "No2"; or like this echo true ? "Yes" : (false ? "No" : "No2"); and why ? ------------------------------------------------------------------------ [2004-11-18 15:40:59] Arne dot Heizmann at csr dot com Description: ------------ The ternary conditional operator (?:) goes wrong when nested two levels deep. When adding parentheses, the bug disappears, even when the parentheses are redundant and shouldn't make any difference. Reproduce code: --------------- echo true ? "Yes" : false ? "No" : "No2"; Expected result: ---------------- "Yes" Actual result: -------------- "No" ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/?id=30825&edit=1