多态性C.

B B
A B
B A

但它打印

Item Item
Item Item
Item Item

代码：

#include <stdio.h>
#include <stdlib.h>
#include <iostream>
using namespace std;

struct Item {
    Item(){}
    virtual void method1 (Item x,Item y) {cout << "Item Itemn";}
};

struct A : public Item {
    A(){}
};

struct B : public Item {
    B(){}
    virtual void method1 (B x,B y) {cout << "B Bn";}
    virtual void method1 (A x,B y) {cout << "A Bn";}
    virtual void method1 (B x,A y) {cout << "B An";}
};

int main ( void ) {
    Item * a[2];
    a[0] = new B; a[1] = new A;
    a[0]->method1(*a[0],*a[0]);
    a[0]->method1(*a[1],*a[0]);
    a[0]->method1(*a[0],*a[1]);
}