Conditional operator differences between C and C++

Question

I read somewhere that the ?: operator in C is slightly different in C++, that there's some source code that works differently in both languages. Unfortunately, I can't find the text anywhere. Does anyone know what this difference is?

Answer 1

The conditional operator in C++ can return an lvalue, whereas C does not allow for similar functionality. Hence, the following is legal in C++:

(true ? a : b) = 1; 

To replicate this in C, you would have to resort to if/else, or deal with references directly:

*(true ? &a : &b) = 1; 

Also in C++, ?: and = operators have equal precedence and group right-to-left, such that:

(true ? a = 1 : b = 2); 

is valid C++ code, but will throw an error in C without parentheses around the last expression:

(true ? a = 1 : (b = 2));