第14周项目2-用文件保存的学生名单

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/*。*Copyright(c)2014,烟台大学计算机学院*All right reserved,*文件名：test.cpp*作者：毕玉堂*完成日期：2015年6月21日*版本号：v1.0*问题描述：*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);  //可以定义input函数替代    friend ostream& operator<<(ostream &out, Student &s); //可以定义display函数替代    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++;   //在读入数据过程中，用静态成员记录下来具体的学生人数和总分和    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;}//返回是否所有课程全过了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;    //将文件中的数据读入到对象数组中    ifstream infile("score.dat",ios::in);  //以输入的方式打开文件    if(!infile)       //测试是否成功打开    {        cerr<<"open error!"<<endl;        exit(1);    }    while(!infile.eof())    {        infile>>stud[i++];   //读数据中，人数等信息自动地记录到静态成员中，见运算符重载的实现    }    infile.close();    //求总分平均并输出    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;}
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