擴展練習4（學生類設計）.設計一個友元函數，按照成績從高到低的順序輸出姓名、學號和成績信息

#include<iostream>
using namespace std;
class CStudent{
private:
	int id_,math_,forlan_,computer_;
	char *name_;
public:
	CStudent(int id=0,char *name=" ",int math=0,int forlan=0,int computer=0):id_(id),name_(name),math_(math),forlan_(forlan),computer_ (computer)
	{}
	int getAverage();
	int getTotal();
	void displayInfor();
	void setName(char * name);
	void setId(int id); 
	friend void getRank(CStudent grade[], int size);
	/*{ 
		int i, j;
		CStudent temp;

		for(i=0; i<size-1; i++){
			for(j=i+1; j<size; j++){
				if(grade[i].getTotal() < grade[j].getTotal()){					
					temp = grade[i];
					grade[i] = grade[j];
					grade[j] = temp;
				}
			}
		}

		for(i=0; i<size; i++){
			grade[i].displayInfor();
		}
	}
	*/
};

int CStudent::getAverage(){
	return getTotal() / 3;
}

int CStudent::getTotal(){
	return math_ + forlan_ + computer_; 
}

void CStudent::displayInfor(){
	cout<<"name: "<<name_ <<"    ID: "<<id_<<"    math: "<<math_<<
		"    foreign langue: "<<forlan_<<"    computer: "<<computer_<<endl;
}

void CStudent::setName(char *name){
	name_ = name;
}

void CStudent::setId(int id){
	id_ = id;
}

void getRank(CStudent grade[], int size){ 
	int i, j;
	CStudent temp;
	for(i=0; i<size-1; i++){
		for(j=i+1; j<size; j++){
			if(grade[i].getTotal() < grade[j].getTotal()){					
				temp = grade[i];
				grade[i] = grade[j];
				grade[j] = temp;
			}
		}
	}

	for(i=0; i<size; i++){
		grade[i].displayInfor();
	}
}

void main()
{
	CStudent *grade = new CStudent[3];
	
	grade[0] = CStudent(1,"hy1",1,3,3);
	grade[1] = CStudent(2,"hy2",2,3,3);
	grade[2] = CStudent(3,"hy3",3,3,3);

	getRank(grade, 3);
	delete []grade;
	return;
} 

轉自http://bbs.csdn.net/topics/390477302?page=1#post-394666155