VS的对象内存分析:
/d reportSingleClassLayout+类名
使用方法:项目 -- 属性 -- C/C++ -- 命令行--其他选型(D) 添加命令.如图所示:
Father类:
class Father { public: virtual void Func1() { cout << "Father::Func1" << endl; } virtual void Func2() { cout << "Father::Func2" << endl; } virtual void Func3() { cout << "Father::Func3" << endl; } void Func4() { cout << "Father::Func4" << endl; } public: int x = 200; int y = 300; static int z; }; int Father::z = 0;
Father的内存分析:
/d reportSingleClassLayoutFather
Son类: public Father
class Son:public Father { public: void Func1() { cout << "Son::Func1" << endl; } virtual void Func5() { cout << "Son::Func5" << endl; } private: int m = 400; int n = 500; };
Son类的内存分析:
/d reportSingleClassLayoutSon
子类的虚函数表构建过程:
(1)直接复制父类的虚函数表
(2)如果子类重写了父类的某个虚函数,那么就在这个虚函数表中进行相应的替换
(3)如果子类中添加了新的虚函数,就把这个虚函数添加到虚函数的表中(在尾部添加)
注意:所有子类共用同一张虚函数表
main函数:
int main(void) { Son son; Father* father = &son; cout << "----Father* father = &son----" << endl; son.Func1(); son.Func2(); son.Func3(); son.Func4(); son.Func5(); Father* son2 = new Son(); cout << "----Father* son2 = new Son()----" << endl; son2->Func1(); son2->Func2(); son2->Func3(); son2->Func4(); //son2->Func5();//错误使用 return 0; }
结果:
全部代码(测试):
#include<iostream> using namespace std; //vs的对象内存分析：/d1 reportSingleClassLayout+类名 class Father { public: virtual void Func1() { cout << "Father::Func1" << endl; } virtual void Func2() { cout << "Father::Func2" << endl; } virtual void Func3() { cout << "Father::Func3" << endl; } void Func4() { cout << "Father::Func4" << endl; } public: int x = 200; int y = 300; static int z; }; int Father::z = 0; class Son:public Father { public: void Func1() { cout << "Son::Func1" << endl; } virtual void Func5() { cout << "Son::Func5" << endl; } private: int m = 400; int n = 500; }; typedef void(*func)(void); void test(void) { Father father; cout << "sizeof(father): " << sizeof(father) << endl; cout << "(int*)&father: " << (int*)&father << endl; cout << "&father: " << &father << endl; int* vptr = (int*)*(int*)(&father); cout << "调用虚函数Func1:" << endl; ((func) * (vptr + 0))(); cout << "调用虚函数Func2:" << endl; ((func) * (vptr + 1))(); cout << "调用虚函数Func3:" << endl; ((func) * (vptr + 2))(); cout << "father.x地址: " << endl; cout << &father.x << endl; cout << (int*)((int)&father + 4) << endl; cout << "father.x:" << endl; cout << father.x << endl; cout << *(int*)((int)&father + 4) << endl; cout << "father.y地址: " << endl; cout << &father.y << endl; cout << (int*)((int)&father + 8) << endl; cout << "father.y:" << endl; cout << father.y << endl; cout << *(int*)((int)&father + 8) << endl; } int main(void) { test(); Son son; Father* father = &son; cout << "----Father* father = &son----" << endl; son.Func1(); son.Func2(); son.Func3(); son.Func4(); son.Func5(); Father* son2 = new Son(); cout << "----Father* son2 = new Son()----" << endl; son2->Func1(); son2->Func2(); son2->Func3(); son2->Func4(); //son2->Func5();//错误使用 return 0; }
