Redirecting output to file then back to console in C++

Question

The task is to read input from input.txt and write the output to output.txt. However on completion of the above tasks, further instructions/output should now be displayed to the console.

Came to know about freopen() in c++ which works fine for the first half of the given task. But unfortunately, I have no idea how to redirect the output back to the console again.

void writeIntoFile(){

   freopen("input.txt","r",stdin); // Task 1. Reading from input.txt file
   freopen("output.txt","w",stdout); // Task 2. Writing to output.txt file
   printf("This sentence is redirected to a file.");
   fclose(stdout);
   printf("This sentence is redirected to console"); // Task 3. Write further output to console

}

What I expected from fclose() was that it would end up writing into the text file and would hence further write the output into the console, but it doesn't. How can I achieve task 3 as well.

Answer 1

Probably what you are looking for is rdbuf() as mentioned by doomista in the comments.

Here is a way to redirect Output.

#include <iostream>
#include <fstream>

int main()
{
    /** backup cout buffer and redirect to out.txt **/
    std::ofstream out("out.txt");

    auto *coutbuf = std::cout.rdbuf();
    std::cout.rdbuf(out.rdbuf());

    std::cout << "This will be redirected to file out.txt" << std::endl;

    /** reset cout buffer **/
    std::cout.rdbuf(coutbuf);

    std::cout << "This will be printed on console" << std::endl;

    return 0;
}