C++里的类中顺序问题#include <iostream>#include <string>using namespace std;class Teacher2;class Student2{private: int num; float score;public: Student2(int n, float s); void display(Teacher2& t);};Student2::Student2(int n, float s){ num = n; score = s;}class Teacher2{public: friend void Student2::display(Teacher2& t); Teacher2(string m);private: string num;};Teacher2::Teacher2(string m){ num = m;}void Student2::display(Teacher2& t){ cout << "学生num为：" << num << " " << "学生score为：" << score << endl; cout << "老师num为：" << t.num << endl;}int main(){ Student2 s1(1001, 90.5), s2(1002, 80), s3(1003, 70.5); Teacher2 t1("20010761"), t2("20024322"), t3("20035673"); s1.display(t1); s2.display(t2); s3.display(t3); return 0;}注意display的位置