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;
}
原文：http://www.cnblogs.com/icode-girl/p/5734296.html