谁教教我这个C语言怎么做?

#include<iostream>
#include<sstream>
#include<string>
#include<iomanip>
using namespace std;

class ClaAchievement
{
public:
    ClaAchievement(){}
    double StudentAchievementAvg(){return (CourseA+CourseB+CourseC)/3;}
    static void CourseAchievementAvg();
    static void display();
    friend istream& operator>>(istream& in,ClaAchievement& PP);
    friend ostream& operator<<(ostream& out,ClaAchievement& TT);  
private:
    static int Number;
    static float CourseASum;
    static float CourseBSum;
    static float CourseCSum;
    char name[10];
    long ID;
    int CourseA,CourseB,CourseC;                  
};

int ClaAchievement::Number=0;
float ClaAchievement::CourseASum=0;
float ClaAchievement::CourseBSum=0;
float ClaAchievement::CourseCSum=0;

void ClaAchievement::CourseAchievementAvg()
{cout<<"课程1: "<<CourseASum/3<<"  "
<<"课程2: "<<CourseBSum/3<<"  "
<<"课程3: "<<CourseCSum/3<<endl;}

istream& operator>>(istream& in,ClaAchievement& PP)
{
    ClaAchievement::Number++;     
    string str;
    getline(in,str);
    stringstream sin(str);
    sin>>PP.name>>PP.ID>>PP.CourseA>>PP.CourseB>>PP.CourseC;
    ClaAchievement::CourseASum+=PP.CourseA;
    ClaAchievement::CourseBSum+=PP.CourseB;
    ClaAchievement::CourseCSum+=PP.CourseC;
    return in;         
}

ostream& operator<<(ostream& out,ClaAchievement& TT)
{
    return out<<setw(10)<<TT.name<<"  "<<setw(6)<<TT.ID<<"  "<<setw(4)<<TT.CourseA<<"  "
        <<setw(4)<<TT.CourseB<<"  "<<setw(4)<<TT.CourseC<<"  "<<setw(4)<<TT.StudentAchievementAvg()<<endl;      
}

void ClaAchievement::display()
{
    cout<<"****班成绩统计: "<<endl
        <<"============================================"<<endl
        <<"学生人数："<<ClaAchievement::Number-1<<endl;
    ClaAchievement::CourseAchievementAvg();
    cout<<"============================================"<<endl;   
}

int main()
{
    int num;
    cout<<"输入学生人数：";
    cin>>num;
    ClaAchievement* ptr=new ClaAchievement[num];
    cout<<"学生姓名 学号 课程1成绩 课程2成绩 课程3成绩：(空格隔开)"<<endl;
    for (int i=0;i!=num+1;++i)
        cin>>ptr[i];
    cout<<endl<<"********************************************************************************"<<endl
        <<"☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆☆"<<endl
        <<"********************************************************************************"<<endl<<endl;
    ClaAchievement::display();
    for (int i=1;i!=num+1;++i)
    {
        cout<<ptr[i];  
    }   
    delete []ptr;
    system("pause");   
    getchar();
    return 0;
}