How can I redirect stdout to some visible display in a Windows Application?

Question

I have access to a third party library that does \"good stuff.\" It issues status and progress messages to stdout. In a Console application I can see these messages just f

Answer 1

You could do something like this with cout or cerr:

// open a file stream
ofstream out("filename");
// save cout's stream buffer
streambuf *sb = cout.rdbuf();
// point cout's stream buffer to that of the open file
cout.rdbuf(out.rdbuf());
// now you can print to file by writing to cout
cout << "Hello, world!";
// restore cout's buffer back
cout.rdbuf(sb);

Or, you can do that with a std::stringstream or some other class derived from std::ostream.

To redirect stdout, you'd need to reopen the file handle. This thread has some ideas of this nature.

Answer 2

Thanks to the gamedev link in the answer by greyfade, I was able to write and test this simple piece of code

AllocConsole();

*stdout = *_tfdopen(_open_osfhandle((intptr_t) GetStdHandle(STD_OUTPUT_HANDLE), _O_WRONLY), _T("a"));
*stderr = *_tfdopen(_open_osfhandle((intptr_t) GetStdHandle(STD_ERROR_HANDLE), _O_WRONLY), _T("a"));
*stdin = *_tfdopen(_open_osfhandle((intptr_t) GetStdHandle(STD_INPUT_HANDLE), _O_WRONLY), _T("r"));


printf("A printf to stdout\n");
std::cout << "A << to std::cout\n";
std::cerr << "A << to std::cerr\n";
std::string input;
std::cin >> input;

std::cout << "value read from std::cin is " << input << std::endl;

It works and is adequate for debugging. Getting the text into a more attractive GUI element would take a bit more work.