C++ - How to fix “Debug Assertion Failed! -__IOINFO_TM_ANSI ” message when opening UTF-8 Unicode files

If you getting a error message with following pop-up in Visual Studio solution for C++ when using SetConsoleOutputCP(CP_UTF8) or _setmode(_fileno(stdin), _O_U8TEXT). 

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Microsoft Visual C++ Debug Library
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Debug Assertion Failed!

Expression: ( (_Stream->_flag & _IOSTRG) || 

( fn = _fileno(_Stream), ( (_textmode_safe(fn) == __IOINFO_TM_ANSI) 

&& !_tm_unicode_safe(fn))))

For information on how your program can cause an assertion
failure, see the Visual C++ documentation on asserts.

When debugging the following code, it will give you the above error.

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int main(int argc, char* argv[]) { //https://alfps.wordpress.com/2011/12/08/unicode-part-2-utf-8-stream-mode/ // Set console code page to UTF-8 so console known how to interpret string data SetConsoleOutputCP(CP_UTF8); // Enable buffering to prevent VS from chopping up UTF-8 byte sequences setvbuf(stdout, nullptr, _IOFBF, LINESIZE); std::cout << "Latin Capital Letter O with Diaeresis Ö "; return EXIT_SUCCESS; }

Solution : Change this line of code wcout for all your statements to stdout. 

std::wcout << "Latin Capital Letter O with Diaeresis Ö ";