C++类本质

01 Dec 2021

#include<windows.h>
#include<stdio.h>

class Test
{
public:
    int a;
    int b;
    int add()
    {
        return a + b;
    }
    int sub()
    {
        return a - b;
    }
    int mul()
    {
        return a * b;
    }
    int div()
    {
        return a / b;
    }

    Test()
    {
    }

    Test(int a,int b)
    {
        this->a = a;
        this->b = b;
    }

    ~Test()
    {
        this->a = 0;
        this->b = 0;
    }
};

class SubTest:Test
{
public:
    int c;
    int d;

    SubTest(int a, int b, int c, int d)
    {
        this->a = a;
        this->b = b;
        this->c = c;
        this->d = d;
    }
};

int main()
{
    //Test t(1,2);
    SubTest t(1,2,3,4);
    //t.add(); 
    return 0;
}

/*

类实例化出来的对象一般在创建它的函数栈帧的缓冲区(ebp-4,ebp-8,ebp-C)中
调用成员方法(包括构造器)时会先将参数PUSH进栈再lea ecx,对象地址(一般为该层函数栈缓冲区ebp-8中)；这叫做__thiscall(内平栈，从右到左堆栈传参(32位)，最后传对象指针(this指针，通过ecx传，保存在成员函数栈缓冲区ebp-8处))

*/