winapi - I need getRTF() example for win32 api richedit control

Question

I saw in MSDN that Rich edit control Win 32 API have function to get rich text format that its contents.

http://msdn.microsoft.com/en-us/library/aa247997%28v=vs.60%29.aspx

But in MSDN have no example so that I don't know how to use this function. I need get text in Rich Edit with full rich text format as a string. Please help me. Thanks so much.