小编Mr.*_*cky的帖子

首先,我知道sizeof取决于机器和编译器的实现.我使用的是Windows 8.1.x64,gcc 5.3.0.,没有标志传递给编译器.
我的大学讲座中有以下代码:

#include <iostream>
class A
{
    public:
        int a;
        int b;
        A(){ a = 1; b = 2; }
};

class S1 : public A {
    public:
        int x1;
        S1(){ x1 = 5;}
};

class S2 : public A {
    public:
        int x2;
        S2(){ x2 = 6;}
};

class S12 : public S1, public S2 {
    public:
       int x12;
       S12(){ x12 = 7;}
};

int main()
{
    std::cout << "S1: " << sizeof(A) << std::endl;
    std::cout << …