Question

http://msdn.microsoft.com/en-us/library/windows/desktop/ms684969(v=vs.85).aspx
error C2664: ‘ReadConsoleOutputCharacterW’ : cannot convert parameter 2 from ‘char *’ to ‘LPWSTR’

#include <windows.h>
#include <stdio.h>

int main(void)
{
    HANDLE hOut;
    char letter;
    char letters[5];
    DWORD numberRead;
    COORD where_;

    SetConsoleTitle(L"Hello!");
    hOut = GetStdHandle(STD_OUTPUT_HANDLE);
    where_.X = 0;
    where_.Y = 0;
    ReadConsoleOutputCharacter(hOut, &letter, 1, where_, &numberRead);
    printf("letter at (0,0) is %c letter", letter);
    return 0;
}

Answer 1

It seems you are compiling with unicode support enabled (because ReadConsoleOutputCharacter resolves to ReadConsoleOutputCharacterW, otherwise it would resolve to ReadConsoleOutputCharacterA).

This means all strings and characters used with any WinAPI functions need to be wide characters WCHAR instead of char and LPWSTR instead of LPSTR, …. Or you disable unicode by undefining the appropriate preprocessor symbols (UNICODE and _UNICODE, I think). But in this case your SetConsoleTitle call won’t work anymore, as you explicitly pass it a wide string.

But the most flexible would be to use TCHAR instead of char and LPTSTR instead of LPSTR and the like. These are just defined to the correct types depending on the definition of the UNICODE preprocessor symbol. In this case the code stays widely independent of unicode support. But in this case you have to wrap all string literals in the _T, T or TEXT macro:

//non-unicode
const char *str = "something";

//unicode
const WCHAR *str = L"something";

//unicode-agnostic
const TCHAR *str = _T("something");

See here for an introduction to the problem.

If you don’t really need unicode support and only need some simple WinAPI functions and want them to interface well with the C standard library (like in your case it seems), it would be the best idea to just undefine UNICODE and _UNICODE and use standard chars. In this case also remove the L modifier from your string literals.