Example for https://stackoverflow.com/q/47418541/827263

#include <iostream>
#include <cstddef>
int main() {
    struct A {
        char c;
        short s;
        char c2;
        int i;
    };
    A obj;
    std::cout << "sizeof (A) = " << sizeof (A) << "\n";
    std::cout << "    char  c  at offset " << offsetof(A, c)  << " size " << sizeof obj.c  << "\n";
    std::cout << "    short s  at offset " << offsetof(A, s)  << " size " << sizeof obj.s  << "\n";
    std::cout << "    char  c2 at offset " << offsetof(A, c2) << " size " << sizeof obj.c2 << "\n";
    std::cout << "    int   i  at offset " << offsetof(A, i)  << " size " << sizeof obj.i  << "\n";
}

// Output on my system (g++, Linux x86_64):
//
// sizeof (A) = 12
//     char  c  at offset 0 size 1
//     short s  at offset 2 size 2
//     char  c2 at offset 4 size 1
//     int   i  at offset 8 size 4