Arithmetic operator return type

Question

int main(int argc, char **argv)
{
    unsigned char a = 10, b = 100;
    std::cout<<sizeof(a-b)<<endl;
    return 1;
}

Output: 4

What is the return data type?

Answer 1

Arithmetic is always performed at least with int precision in C++. a and b are both promoted to int and the result of the subtraction is of type int.

There are a set of rules used to determine the type used for an arithmetic operation; MSDN has a handy table listing the rules.