xsgetn(s, count)of the most derived class.
countcharacters from the input sequence and stores them into a character array pointed to by
s. The characters are read as if by repeated calls to sbumpc(). That is, if less than
countcharacters are immediately available, the function calls uflow() to provide more until traits::eof() is returned.
 Return value
The number of characters successfully read.
|This section is incomplete
Reason: no example
 See also
| invokes xsputn()
(public member function)