C++证明vptr指针的存在的demo

#include 
using namespace std;

class A {
public:
    void print() {
        printf("An");
    }
protected:
private:
    int a;
};

class A2 {
public:
    virtual void print() {
        printf("An");
    }
protected:
private:
    int a;
};



void main() {

    printf("sizeof(A):%dn", sizeof(A));  // sizeof(A) : 4
    printf("sizeof(A2):%dn", sizeof(A2));  // sizeof(A2) : 8  // 多出的4个字节是vptr指针


    system("pause");
}