摘要：先看这个例子：#include<iostream>using namespace std;class a{public:a(int m){b=m;cout<<"class a"<<endl;}~a(){cout<<"delete class a"<<endl;}friend void display(a x){cout<<x.b<<endl;}private:int b;};void main(){class a a1(3);display(a1);system(&quo 阅读全文