C++流类

/*操作符重载*/
ostream& operator<< (ostream &o, diy &d){
    o<<d.fenzi<<'/'<<d.fenmu<<endl;
    return o;
}
diy a;
cout<
/*右向左，遇到重载操作符，将对象重定向到o里，返回o，在重定向到标准输出*/
cin>>a;

#include <fstream>
#include <iostream>
using namespace std;
int main(){
    char a;
    char buffer[199];
    ifstream i("./3.cpp");
    ofstream o("./c++/1.cpp");
    //while(i>>a)
    //o<<a;
    //while(i>>a)
    //cout<<a;
    while(!i.eof()){
        i.getline(buffer,199);//遇到换行符截止
        cout<<buffer<<endl;//不读换行符所以加上endl
    }
    i.close();
    o.close();
}

/*流操作粒度:字符串对象*/
#include <fstream>
#include <iostream>
using namespace std;
int main(){
    string line;
    ifstream i("./3.cpp");
    ofstream o("./c++/1.cpp");
    while(!i.eof()){
        getline(i,line);
        o<<line<<endl;
    }
    i.close();
    o.close();
}

#include <fstream>
#include <iostream>
using namespace std;
int main(){
    char a;
    ifstream i("./3.cpp");
    ofstream o("./c++/1.cpp");
    //while(i>>a)
    //o<<a;
    while(i>>a)
    cout<<a;
    i.close();
    o.close();
}