redirect stdout/stderr to file under unix c++ - again

Question

What I want to do

redirect stdout and stderr to one or more files from inside c++

Why I need it

I am using an external, pr

Answer 1

I was inspired by @POW and @James Kanze 's answers and put together a little RAII class for redirecting std::cout to a file. It is intended to demonstrate the principle.

Code:

#include 
#include 
#include 

// RAII for redirection
class Redirect {
    public:
    
    explicit Redirect(const std::string& filenm):
        _coutbuf{ std::cout.rdbuf() },   // save original rdbuf
        _outf{ filenm }
    {
        // replace cout's rdbuf with the file's rdbuf
        std::cout.rdbuf(_outf.rdbuf());
    }
    
    ~Redirect() {
        // restore cout's rdbuf to the original
        std::cout << std::flush;
        _outf.close();    ///< not really necessary
        std::cout.rdbuf(_coutbuf); 
    }
    
    private:
    
    std::streambuf* _coutbuf;
    std::ofstream _outf;
};

// == MAIN ==

int main(int argc, char* argv[]) {
    std::cout << "This message is printed to the screen" << std::endl;
    {
        // scope for the redirection
        Redirect redirect{ "output.txt" };
        std::cout << "This message goes to the file" << std::endl;
    }
    std::cout << "Printing to the screen again" << std::endl;
}

Output:

This message is printed to the screen

Printing to the screen again

Contents of the file "output.txt":

This message goes to the file