c++文件输入输出流fstream，对输入>>和输出<<重载

1. fstream 继承自iostream --> 要包含头文件#include<fstream>

2. 建立文件流对象

3. 打开文件夹

4. 测试是否打开成功

5. 进行读写操作

6. 关闭文件

#include<iostream>

#include<fstream>



using namespace std;



int main(){

    ifstream ifile;

    ofstream ofile;

    

    ifile.open("d:\\fileIn.txt");

    ofile.open("d:\\fileOut.txt");



    if (ifile.fail() || ofile.fail()){

        cerr << "open file fail\n";

        return EXIT_FAILURE;

    }



    char ch;

    ch = ifile.get();

    cout << ch << endl;

    while (!ifile.eof()){

        ofile.put(ch);

        ch = ifile.get();

    }



    ifile.close();

    ofile.close();



    int i;

    cin >> i;

    return 0;

}

View Code

输入三个学生的姓名，学好，年龄和住址，并存入文件中，再从文件中读出来：

 1 #include<iostream>

 2 #include<fstream>

 3 using namespace std;

 4 

 5 class student{

 6 public: 

 7     char name[10];

 8     int num;

 9     int age;

10     char addr[20];

11     friend ostream & operator<<(ostream &out, student &s);

12     friend istream & operator>>(istream &in, student &s);

13 };

14 ostream & operator<<(ostream &out, student &s){

15     out << s.name << " " << s.num << " " << s.age << " " << s.addr << endl;

16     return out;

17 }

18 istream & operator>>(istream &in, student &s){

19     in >> s.name >> s.num  >> s.age >> s.addr;

20     return in;

21 }

22 int main(){

23     ifstream ifile;

24     ofstream ofile;

25     ofile.open("d:\\s.txt");

26 

27     student s;

28     for (int i = 1; i <= 3; i++){

29         cout << "请输入第" << i << "个学生的姓名 学号 年龄 地址" << endl;

30         cin >> s;   //调用>>运算符重载函数，输入学生信息

31         ofile << s; //调用<<运算符重载函数，将学生信息写入到文件中

32     }

33     ofile.close();

34 

35     cout << "\n读出文件内容" << endl;

36     ifile.open("d:\\s.txt");

37     ifile >> s;

38     while (!ifile.eof()){

39         cout << s;

40         ifile >> s;

41     }

42     ifile.close();

43     int i;

44     cin >> i;

45     return 0;

46 }

View Code

结果：