文件操作

文件操作的三大类：ofsteam写,ifsteam读,fsteam读写

# include<fstream>
#include<iostream>
using namespace std;

int main() {
    ofstream ofs;
    ofs.open("abc.txt", ios::out);
    ofs << "1" << endl;
    ofs << "2" << endl;
    ofs << "3" << endl;
    ofs.close();


    ifstream ifs;
    ifs.open("abc.txt", ios::in);
    char buf[1024] = {0};
    while (ifs.getline(buf,sizeof(buf)))
    {
        cout << buf << endl;
    }
}