virtual streambuf* setbuf( char* pr, int nLength );
pr
A pointer to a previously allocated reserve area of length nLength. A NULL value indicates an unbuffered stream.
nLength
The length (in bytes) of the reserve area. A length of 0 indicates an unbuffered stream.
Attaches the specified reserve area to the streambuf object. Derived classes may or may not use this area.
Accepts the request if there is not a reserved area already.
A streambuf pointer if the buffer is accepted; otherwise NULL.