PHP nested conditional operator bug?

Question

   
                return
                    true  ? 'a' :
                    false ? 'b' :
                                                           'c';

This should return 'a', but it doesn't. It returns 'b' instead. Is there a bug in PHP's order of handling the different parts of the conditional operators?

I got the idea from http://stackoverflow.com/questions/1917718/are-multiple-conditional-operators-in-this-situation-a-good-idea where it does seem to work correctly.

(the true and false are for the purpose of the example, of course. in the real code they are statements that evaluate to true and false respectively. yes, i know that for sure)

Answer 1

order of operations:

>>> return true ? 'a' : false ? 'b': 'c';
'b'
>>> return true ? 'a' : (false ? 'b': 'c');
'a'

Answer 2

Suspect it's evaluating (true ? 'a' : false) as the input to the second ternary operator and interpreting 'a' as true. Try bracketing appropriately.

Answer 3

It is recommended that you avoid "stacking" ternary expressions. PHP's behaviour when using more than one ternary operator within a single statement is non-obvious

From the PHP Manual under "Non-obvious Ternary Behaviour".

Ternary operators are evaluated left to right, so unless you add it the braces it doesn't behave as you expect. The following would work though,

return (true ? "a" : (false ? "b" : "c"));