第十六周项目2-文件保存学生名单

/*
*Copyright (c) 2016，烟台大学计算机学院
*All rights reserved.
*文件名称：zwj.cpp
*作    者：张伟晶
*完成日期：2016年6月20日
*版 本 号：v1.0
*
*问题描述：用文件保存学生信息
*输入描述：
*程序输出：
*/
#include <fstream>
#include<iostream>
#include<string>
#include<cstdlib>
using namespace std;

//定义学生类
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);
friend ostream& operator<<(ostream &out, Student &s);
bool pass();
private:
string name;
double cpp;
double math;
double english;
double total;
static int stu_num;  //学生人数，处理为类的静态成员合适
static double total_sum; //学生总分和
};

int Student::stu_num = 0;
double Student::total_sum = 0;
Student::~Student()
{
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)
{
in>>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; //stud[200]为保存数据的对象数组
string sname;
double total_avg;
int i=0;

ifstream infile("score.txt",ios::in);
if(!infile)
{
cerr<<"open error!"<<endl;
exit(1);
}
while(!infile.eof())
{
infile>>stud[i++];
}
infile.close();

if(Student::get_stu_num()>0)
{
total_avg = Student::get_total_sum() / Student::get_stu_num();
ofstream outfile("pass_score.txt",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;
}