how-to-redirect-cin-and-cout-to-files

#include <iostream>

#include <fstream>

#include <string>

void f()

{

    std::string line;

    while(std::getline(std::cin, line))  //input from the file in.txt

    {

        std::cout << line << "\n";   //output to the file out.txt

    }

}

int main()

{

    std::ifstream in("in.txt");

    std::streambuf *cinbuf = std::cin.rdbuf(); //save old buf

    std::cin.rdbuf(in.rdbuf()); //redirect std::cin to in.txt!

    std::ofstream out("out.txt");

    std::streambuf *coutbuf = std::cout.rdbuf(); //save old buf

    std::cout.rdbuf(out.rdbuf()); //redirect std::cout to out.txt!

    std::string word;

    std::cin >> word;           //input from the file in.txt

    std::cout << word << "  ";  //output to the file out.txt

    f(); //call function

    std::cin.rdbuf(cinbuf);   //reset to standard input again

    std::cout.rdbuf(coutbuf); //reset to standard output again

    std::cin >> word;   //input from the standard input

    std::cout << word;  //output to the standard input

}
巴特西

how-to-redirect-cin-and-cout-to-files

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