代码：

#include<iostream>

using namespace std;
 
class interface1//爸爸1
{
public :
	virtual int add(int a,int b){
		return a+b;	
	}
	virtual void printf(){
		cout<<"I am interface1."<<endl;
	}
};
class interface2//爸爸2
{
public:
	virtual int mul(int a, int b){
		return a*b;
	} 
	virtual void printf(){
		cout<<"I am interface2."<<endl;
	}
};
//在工程中我们一般不会用到多继承的语法，因为多继承的菱形结构会发生二义性
//
class A:public interface1,public interface2//A继承爸爸1 爸爸2，以及其中的虚函数
{
public:
	virtual int mul(int a,int b)
	{
		this->m_a = a;
		this->m_b = b;
		return a*b;
	}
	virtual int add(int a, int b)
	{
		this->m_a = a;
		this->m_b = b;
		return a+b;
	}
private:
	int m_a;
	int m_b;
};
int main()
{
	interface1 *t1=NULL;
	interface2 *t2 = NULL;
	A a1;
 
	t1 = &a1;
	cout << t1->add(1, 1) << endl;
	t1->printf();
 
	t2 = &a1;
	t2->mul(3, 9);
	t2->printf();
	a1.printf(); //不合法
	return 0;
}