C++对象内存布局（一）

时间：2015-07-05 00:51:39 阅读：139 评论：0 收藏：0 [点我收藏+]

标签：

一、前言

　　在看了皓哥的C++对象的布局之后：http://blog.csdn.net/haoel/article/details/3081328。感觉自己还是总是不能记得很清楚，故在此总结一下C++对象的内存布局，一遍以后及时复习。

二、

单一非虚继承：有成员变量，有虚函数和虚函数的覆盖，不是虚拟继承

技术分享

源码如下：

#include <iostream>
using namespace std;

class Parent
{
public:
    int iparent;
    Parent() : iparent(10) {}
    virtual void f()
    {
        cout << "Parent::f()" << endl;
    }
    virtual void g()
    {
        cout << "Parent::g()" << endl;
    }
    virtual void h()
    {
        cout << "Parent::g()" << endl;
    }
};

class Child : public Parent
{
public:
    int ichild;
    Child() : ichild(100) {}
    virtual void f()
    {
        cout << "Child::f()" << endl;
    }
    virtual void g_child()
    {
        cout << "Child::g_child()" << endl;
    }
    virtual void h_child()
    {
        cout << "Child::h_child()" << endl;
    }
};

class GrandChild : public Child
{
public:
    int igrandchild;
    GrandChild() : igrandchild(1000) {};
    virtual void f()
    {
        cout << "GrandChild::f()" << endl;
    }
    virtual void g_child()
    {
        cout << "GrandChild::g_child()" << endl;
    }
    virtual void h_gradnchild()
    {
        cout << "GrandChild::h_grandchild()" << endl;
    }
};
int main(int argc, char **argv)
{
    GrandChild gc;
    typedef void(*Fun)(void);
    Fun pf;

    cout << "[0] GrandChild::vfptr->" << endl;
    cout << "    [0]";
    pf = (Fun)*(int *)*(int *)&gc;
    pf();

    cout << "    [1]";
    pf = (Fun)*((int *)*(int *)&gc + 1);
    pf();

    cout << "    [2]";
    pf = (Fun)*((int *)*(int *)&gc + 2);
    pf();

    cout << "    [3]";
    pf = (Fun)*((int *)*(int *)&gc + 3);
    pf();

    cout << "    [4]";
    pf = (Fun)*((int *)*(int *)&gc + 4);
    pf();

    cout << "    [5]";
    pf = (Fun)*((int *)*(int *)&gc + 5);
    pf();

    cout << "[1] Parent.iparent = " << (int)(*((int *)&gc + 1)) << endl;
    cout << "[2] Child.ichild = " << (int)(*((int *)&gc + 2)) << endl;
    cout << "[3] GrandChild.igrandchild = " << (int)(*((int *)&gc + 3)) << endl;
    return 0;
}

代码运行结果如下：

[0] GrandChild::vfptr->
        [0]GrandChild::f()
        [1]Parent::g()
        [2]Parent::g()
        [3]GrandChild::g_child()
        [4]Child::h_child()
        [5]GrandChild::h_grandchild()
[1] Parent.iparent = 10
[2] Child.ichild = 100
[3] GrandChild.igrandchild = 1000