第16周项目2-用文件保存学生名单

/*
*Copyright(C) 2016,计算机与控制工程学院
*All rights reserved.
*文件名:test.cpp
*作者:张志新
*完成日期:2016年6月23日
*版本号:v1.0
*
*问题描述:用文件保存学生名单
*/
#include <fstream>
#include<iostream>
#include<string>
#include<cstdlib>
using namespace std;
class Student
{
public:
Student() {};
~Student();
double get_total();
static int get_stu_num();
static double get_total_sum();
friend istream& operator>>(istream &in, Student &s);//重载
friend ostream& operator<<(ostream &out, Student &s);
bool pass();
private:
string name;
double cpp;
double math;
double english;
double total;
static int stu_num;
static double total_sum;
};

int Student::stu_num = 0;
double Student::total_sum = 0;
Student::~Student()//析构函数
{
total_sum-=total;
stu_num--;
}

double Student::get_total()
{
return total;
}

int Student::get_stu_num()
{
return stu_num;
}

double Student::get_total_sum()
{
return total_sum;
}

istream& operator>>(istream &in, Student &s)
{
cin>>s.name>>s.cpp>>s.math>>s.english;
s.total=s.cpp+s.math+s.english;
Student::stu_num++;
Student::total_sum+=s.total;
return in;
}

ostream &operator<<(ostream &out, Student &s)
{
out<<s.name<<"\t";
out<<s.cpp<<"\t";
out<<s.math<<"\t";
out<<s.english<<"\t";
out<<s.total;
return out;
}

bool Student::pass()
{
return cpp>=60 && math>=60 && english>=60;
}

int main()
{
Student stud[200],t;
string sname;
double total_avg;
int i=0;
ifstream infile("score.dat",ios::in);
if(!infile)//文件打开不成功
{
cerr<<"open error!"<<endl;
exit(1);
}
while(!infile.eof())
{
infile>>stud[i++];
}
infile.close();//关闭文件

if(Student::get_stu_num()>0)
{
total_avg = Student::get_total_sum() / Student::get_stu_num();
ofstream outfile("pass_score.dat",ios::out);
if(!outfile)
{
cerr<<"open error!"<<endl;
exit(1);
}

for(i=0; i<Student::get_stu_num(); i++)
{
if(stud[i].get_total()>total_avg&&stud[i].pass())
{
outfile<<stud[i]<<endl;
}
}
outfile.close();
cout<<"请到文件pass_score.dat中查看名单："<<endl;
}
return 0;
}