winapi - Win32 Application Programming C++, Error with parameter Type LPCWSTR

Question

I am constructing a program using the Win32 Application on Visual Studio 2013. From the tutorials I have read, I know this following code is correct, but I don't know where to change the parameter type to read the following:

case WM_CREATE:
{
    hEdit = CreateWindowEx(WS_EX_CLIENTEDGE, "Edit", "",
        WS_CHILD | WS_VISIBLE | ES_MULTILINE | ES_AUTOHSCROLL |
        ES_AUTOVSCROLL, 50, 100, 300, 300, hWnd, (HMENU)IDC_EDIT_BOX, 
        NULL, NULL);

The compiler highlights "Edit" and gives me this error:

Error 1 error C2664: 'HWND CreateWindowExW(DWORD,LPCWSTR,LPCWSTR,DWORD,int,int,int,int,HWND,HMENU,HINSTANCE,LPVOID)' : cannot convert argument 2 from 'const char [5]' to 'LPCWSTR'

Answer 1

You are compiling with UNICODE defined. That means that CreateWindowEx is an alias for CreateWindowExW, the wide character version. Either:

1. Supply wide character text, or
2. Call CreateWindowExA, or
3. Compile for ANSI.

Personally I would suggest option 1. Your code would become:

CreateWindowEx(WS_EX_CLIENTEDGE, L"Edit", L"",
  WS_CHILD | WS_VISIBLE | ES_MULTILINE | ES_AUTOHSCROLL | ES_AUTOVSCROLL, 
  50, 100, 300, 300, hWnd, (HMENU)IDC_EDIT_BOX, NULL, NULL);

The L prefix to your string literals is used to specify a wide character literal.