第十六周C++【任务二】学生成绩排序

【任务2】学生成绩排序
文件score.dat 中保存的是100 名学生的姓名和C++课、高数和英语成绩。
（1）定义学生类，其中包含姓名、C++课、高数和英语成绩及总分、均分数据成员，成员函数根据
需要确定。
（2）读入这名学生的成绩，用对象数组进行存储。
（3）求出各科和总分的最高分。
（4）请按总分的降序（高成绩在前，低成绩在后）排序
（5）在屏幕上显示各科及总分的最高分，排序后的成绩单（包括总分）保存到文件odered_score.dat
中

 

#include<iostream> #include <string>using namespace std;#include<fstream>class Student{public:double get_total();double get_average();void get_name(string name);void get_c_score(double c_score);void get_m_score(double m_score);void get_e_score(double e_score);friend void input(Student *stu) ;friend void output(Student *stu);friend void output_max(Student *stu);friend void paixu(Student *stu);private:string name;double c_score;double m_score;double e_score;double total;double average;};double Student::get_total(){(this->total) = (this->c_score + this->e_score + this->m_score);return (this->total);}double Student::get_average(){(this->average) = (this->c_score + this->e_score + this->m_score)/3;return (this->average);}void Student::get_name(string name){this->name = name;}void Student::get_c_score(double c_score){this->c_score = c_score;}void Student::get_m_score(double m_score){this->m_score = m_score;}void Student::get_e_score(double e_score){this->e_score = e_score;}void input(Student stu[]){string name;int i;double c_score;double m_score;double e_score;ifstream inFile("score.dat",ios::in);if(!inFile){cerr<<"open error!"<<endl;exit(1);}for( i=0;i<100;++i){inFile>>name;stu[i].get_name( name);inFile>>c_score;stu[i].get_c_score( c_score);inFile>>e_score;stu[i].get_e_score( e_score);inFile>>m_score;stu[i].get_m_score( m_score);}inFile.close();}void output(Student *stu){ofstream writeFile("odered_score.dat",ios::out);if(!writeFile){cerr<<"open error!"<<endl;exit(1);}for(int i=0;i<100;++i){writeFile<<stu[i].name;cout<<stu[i].name<<" ";writeFile<<stu[i].c_score;cout<<stu[i].c_score<<" ";writeFile<<stu[i].e_score;cout<<stu[i].e_score<<" ";writeFile<<stu[i].m_score;cout<<stu[i].m_score<<" ";writeFile<<stu[i].average;cout<<stu[i].average<<" ";writeFile<<stu[i].total;cout<<stu[i].total<<" ";cout<<endl;}writeFile.close();}void output_max(Student *stu){double max1,max2,max3,max4;max1=stu[0].c_score;max2=stu[0].m_score;max3=stu[0].e_score;max4=stu[0].get_total();for(int i=0;i<100;++i){if(stu[i].c_score>max1){max1=stu[i].c_score;}if(stu[i].m_score>max2){max2=stu[i].m_score;}if(stu[i].e_score>max3){max3=stu[i].e_score;}if(stu[i].get_total()>max4){max4=stu[i].get_total();}}cout<<max1<<endl;cout<<max2<<endl;cout<<max3<<endl;cout<<max4<<endl;}void paixu(Student *stu){Student t;for( int i=0;i<100;++i){stu[i].get_total();stu[i].get_average();}for(int i=0;i<99;++i)for(int j=0;j<99-i;++j){if(stu[i].total<stu[i+1].total){t=stu[i];stu[i]=stu[i+1];stu[i+1]=t;}}}int main(){Student stu[100];     input(stu);output_max(stu);paixu(stu);output(stu);    cout<<endl;  system("PAUSE");      return 0;  }

 

 

积累经验：文件的输入输出是有一定套路的，掌握其方法，万变不离其中。

writeFile<<stu[i].name;这里只是将数据向磁盘文件输出，所以在屏幕上看不见输出结果，要想输出，就加上cout<<stu[i].name<<" ";

这一点与电子词典不同。而且在读入数据时，此处涉及到了传参。