c加加小问题 哪里出错了

#include
using namespace std;
class Student
{public:
Student(int n , float s):num(n),score(s){}
void change (int n,float s){num=n;score=s;}
void display(){cout<<num<<""<<score<<endl;}
private:
int num;
float score;
};
int main()
{Student stud(101,78.5);
stu.display();
stu.change(101,80.5);
stu.display();
return 0;
}

在main函数调用时，实例stu改为stud就可以了，名字写错了。

#include <iostream> 
using namespace std;
class Student
{
    public:
    Student(int n , float s):num(n),score(s){}
    void change (int n,float s){num=n;score=s;}
    void display(){cout<<num<<" "<<score<<endl;}
    private:
    int num;
    float score;
};

    int main()
    {
        Student stud(101,78.5);
        stud.display();
        stud.change(101,80.5);
        stud.display();
        return 0;
    }

你定义的stud 使用的是stu