file_ptr

    A pointer to a file.

 buffer

    A pointer to a character array, or a NULL pointer.

 type

    The buffering type. Use one of the following values defined in
    <stdio.h>: _IOFBF or _IOLBF.

 size

    The number of bytes to be used in buffer by the Compaq C RTL for
    buffering this file. The buffer size must be a minimum of 8192
    bytes and a maximum of 32767 bytes.