You may say.

//#DEFINE UNICODE
#include <Windows.h>

int main()
{
    HANDLE hOut = GetStdHandle(STD_OUTPUT_HANDLE);
    LPTSTR msg = TEXT("Hello, World!n");
    WriteConsole(hOut, msg, lstrlen(msg), NULL, NULL);
}

This works, as long as STDOUT is not redirected, as in main > tmp.txt. Then, WriteConsole() errors, with the format message “The handle is invalid.”. Then, WriteFile() should work, so you may say.

WriteFile(hOut, msg, lstrlen(msg), NULL, NULL);

This is great, except if 1) STDOUT is not redirected, and 2) UNICODE is set. Then it would print H e l l o , , because apparently WriteFile() does not “translate” the characters, it just sends the bytes. Maybe this can be solved by changing the DOS codepage, but it would not to be UTF-16, since Windows calls UTF-16 “UNICODE”. On my computers, the codepages for UTF-16 are not available, so I would not rely on it.

The solution I (ChatGPT 4o) found is to identify if the “file type” of the handle.

if (GetFileType(hOut) == FILE_TYPE_CHAR)
    WriteConsole(hOut, msg, lstrlen(msg), NULL, NULL);
else
    WriteFile(hOut, msg, lstrlen(msg) * sizeof(TCHAR), NULL, NULL);

Still, is this the proper solution? And if possible, what is the proper way of reading STDIN, since it suffers from a similar problem?