4.21

#include<iostream>
#include<string>
using namespace std;
class student{
public:
	student(string a,int b,int c);
	void show()
	{
		cout<<"name:"<<name<<"  id:"<<id<<"  score:"<<score<<"  test:"<<test<<"  number:"<<number<<"  ave:"<<ave<<endl;
	}
private:
	string name;
	int id;
	int score;
	static int test;
	static int number;
	int ave;
};
student::student(string a,int b,int c)
{
	name=a;
	id=b;
	score=c;
	test=test+score;
	++number;
	ave=test/number;
}
int student::test=0;
int student::number=0;
int main()
{
	student k1[2]={
		student("xiaoming",20141165,95),
			student("wanghan",20141164,85)
	};
	for(int i=0;i<2;i++)
		k1[i].show();
	system("pause");
	return 0;
}