#include<iostream>using namespace std;#include"exp3_1.h"int main(){Girl g("sss",20);Boy b("sll",18);g.Print();b.Print();g.VisitBoy(b);// b.VisitGirl(g);return 0;}//頭文件exp3_1.h#include<iostream>#include<string>using namespace std;class Boy; //向前引用class Girl{char name[20]; //類數據成員默認私有int age;public:Girl(char N[],int A); //構造函數~Girl() //析構函數{cout<<"Girl destructing...\n";}void Print();void VisitBoy(Boy &); //在其中訪問Boy類的私有成員};class Boy{char name[20];int age;friend Girl; //將Girl類作為Boy類的友元類public:Boy(char N[],int A);~Boy(){cout<<"Boy destructing...\n";}void Print();// void VisitGirl(Girl &);};//Girl類的成員函數Girl::Girl(char N[],int A) //Girl類的構造函數的實現代碼{strcpy(name,N);age=A;cout<<"Girl constructing...\n";}void Girl::Print() //Girl類的輸出函數實現代碼{cout<<"Girl's name: "<<name<<endl;cout<<"Girl's age: "<<age<<endl;}void Girl::VisitBoy(Boy &boy) //通過Girl類中的VisitBoy函數訪問Boy類中的數據成員{cout<<"Boy's name: "<<boy.name<<endl;cout<<"Boy's age: "<<boy.age<<endl;}//Boy類的成員函數Boy::Boy(char N[],int A){strcpy(name,N);age=A;cout<<"Boy constructing...\n";}void Boy::Print(){cout<<"Boy's name: "<<name<<endl;cout<<"Boy's age: "<<age<<endl;}/*Boy::VisitGirl(Girl &girl){cout<<"Girl's name: "<<girl.name<<endl;cout<<"Girl's age: "<<girl.age<<endl;}*/