Why does sizeof(x++) not increment x?

Question

Here is the code compiled in dev c++ windows:

#include 

int main() {
    int x = 5;
    printf(\"%d and \", sizeof(x++)); // note 1
    print         


        

Answer 1

sizeof is a compile-time builtin operator and is not a function. This becomes very clear in the cases you can use it without the parenthesis:

(sizeof x)  //this also works