C++ fstream stringstream

一、文件输入输出

C/C++

输入：

freopen("in.cpp", "r", stdin);
fclose(stdin);

输出：

freopen("in.cpp", "r", stdout);
fclose(stdout);

C++

输入：

ifstream cin("in.cpp");

cin.close();

输出：

ofstream cout("out.cpp");

cout.close();

二、istringstream ostringstream 和 stringstream.

常用函数：

string str, s;

stringstream str;

stringstring str(s);

str.clear();

str.str(s);

Eg:

#include <sstream>
#include <iostream>
#include <stdio.h>
#include <fstream>
using namespace std;

string str, name, pnum;
string outstr;

int main() {
    ifstream cin("in.cpp");
    ofstream cout("out.cpp");
    stringstream imess;
    stringstream omess;
    while (getline(cin, str)){
        imess.clear();
        omess.str("");
        imess.str(str);

        imess >> name;
        omess << name << ":";

        while(imess >> pnum) {
            omess << " " << pnum;
        }
        cout << omess.str() << endl;
    }
    cin.close();
    cout.close();
    return 0;
}