size of a datatype without using sizeof

Question

I have a data type, say X, and I want to know its size without declaring a variable or pointer of that type and of course without using sizeof oper

Answer 1

This takes into account that a C++ byte is not always 8 binary bits, and that only unsigned types have well defined overflow behaviour.

#include 
int main () {
    unsigned int i = 1;
    unsigned int int_bits = 0;
    while (i!=0) {
        i <<= 1;
        ++int_bits;
    }

    unsigned char uc = 1;
    unsigned int char_bits = 0;
    while (uc!=0) {
        uc <<= 1;
        ++char_bits;
    }

    std::cout << "Type int has " << int_bits << "bits.\n";
    std::cout << "This would be  " << int_bits/8 << " IT bytes and "
              << int_bits/char_bits << " C++ bytes on your platform.\n";
    std::cout << "Anyways, not all bits might be usable by you. Hah.\n";
}

Surely, you could also just #include or .