PHP if / else简写符号 - 多个条件

Question

Please consider the follwing code construction:

condition  ? code_if_true  : 
condition2 ? code_if_true2 : 
             code_if_false;

This doesn't work for PHP whereas it does for JavaScript.

Is there a way to get this working for PHP?

Answer 1

In PHP, the conditional operator is left-associative^[PHP.net], compared to virtually all other languages where it is right-associative.

That's why you need to use parentheses to control the order of evaluation¹:

 condition  ? code_if_true  : 
(condition2 ? code_if_true2 : 
              code_if_false ); 

^{1The order in which which operators are resolved, not when operands are evaluated. The latter is basically undefined[PHP.net]}