C++之文件输入输出

#include <iostream>
#include <fstream>
#include <algorithm>

#define max 105
using namespace std;

struct boy{
    char name[20];
    int china;
    int math;
    int english;

    int sum;
    boy(){
        china = math = english = 0;
    }

}stu[max];

bool operator <(const boy &a,const boy &b)
 {
    return a.sum<b.sum;
 }
int main()
{
    ///创建了读取和写出数据的两个对象
    ifstream input;
    ofstream output;

if(input.fail()){
        cout<<"文件不存在"<<endl;
    }
    else{
    ///打开文件
    input.open("f:\\file1.txt");
    ///Create a file
    output.open("f:\\file2.txt");
    cout<<"文件设置成功"<<endl;
    int i = 0;
    while(!input.eof()){
        input >> stu[i].name >> stu[i].china >> stu[i].math >> stu[i].english;
        stu[i].sum = stu[i].china+stu[i].english+stu[i].math;


        cout<< stu[i].name<<"  "<<stu[i].china<<"  "<<stu[i].math<<"  "<<stu[i].english<<"  "<<stu[i].sum<<endl;
        i++;
        cout<<"读取第"<<i<<"条数据成功"<<endl;
    }
    cout<<"文件读取成功"<<endl;
    ///关闭文件
    input.close();

    sort(stu,stu+i);
    for(int j = 0;j < i;j++){
        output<< stu[j].name<<"  "<<stu[j].china<<"  "<<stu[j].math<<"  "<<stu[j].english<<"  "<<stu[j].sum<<endl;
    }
cout<<"文件写入成功"<<endl;
    output.close();
    }
    return 0;
}