MapViewOfFile and unicode

If you want to create UNICODE text files, you should add a BOM (byte order mark) at the begin of the file to instruct the operating system about the file encoding. If you don't do it, text files are always written on disk as ASCII; it doesn't matter if your code is compiled to use UNICODE.

In other words, the first time you create the text file, prior to any operation on it, you shouyld write two binary bytes on it: 0xFF and 0xFE. You can do it in the following way:

hfile = ::CreateFile(
   TEXT("c:\\1.txt"),
   GENERIC_ALL | FILE_ALL_ACCESS,
   FILE_SHARE_WRITE | FILE_SHARE_READ,
   NULL,
   OPEN_ALWAYS,
   FILE_ATTRIBUTE_NORMAL,
   NULL);
HANDLE hmap = ::CreateFileMapping(
   hfile,
   NULL,
   PAGE_READWRITE,
   0,
   0,
   NULL);
TCHAR *pmap = (TCHAR*)::MapViewOfFile(
   hmap,
   FILE_MAP_ALL_ACCESS,
   0,
   0,
   NULL);
*pmap = (TCHAR)0xFEFF;
TCHAR *tmp = pmap + 1;
lstrcpy(tmp, TEXT("my test"));
::UnmapViewOfFile(pmap);
::CloseHandle(hmap);
::CloseHandle(hfile);

For more informations about BOM you can follow this link: http://www.websina.com/bugzero/kb/unicode-bom.html[^]