第四章

#include<iostream>
#include<string>
using namespace std;
class student
{
public:
 student(string m,int n,double d);
 ~student();
 static void avg();
 void display();
private:
 int no;
 string name;
 double deg;
 static double sum;
 static double num;
};
student::student(string m,int n,double d)
{
 name =m;
 no=n;deg=d;
 sum+=deg;
 num++;
}
student::~student()
{
 
}
double student::sum=0;
double student::num=0;
void student::avg()
{
 cout<<"总分为:"<<sum<<"平均成绩:"<<(sum/num)<<endl;
}
void student::display()
{
 cout<<"姓名:"<<name<<"学号:"<<no<<"成绩:"<<deg<<endl;
}
int main()
{
 student s[3]={
  student("Li",1,89),
  student("chen",2,78),
  student("zheng",3,94)};
 for(int i=0;i<3;i++)
  s[i].display();
 student::avg();
 return 0;
}