Why is the value of the variable not increasing after sizeof(++)

The value temp is 1, but why is temp still 1 after sizeof(++i)? I only know sizeof is an operator.

int main() {
    int i = 1;
    sizeof(i++);
    std::cout << i << std::endl;  // 1
}

>Solution :

sizeof does not evaluate its operand. It determines the operand’s type and returns its size. It is not necessary to evaluate the operand in order to determine it’s size. This is actually one of the fundamental core principles of C++: the types of all objects — and by consequence of all expressions — is known at compile time.

And since the operand does not get evaluated there are no side effects from its evaluation. If you sizeof() something that makes a function call the function does not actually get called: sizeof(hello_world()) won’t call this function, but just determines the size of whatever it returns.