xsgetn(s, count) of the most derived class.
characters from the input sequence and stores them into a character array pointed to by
. The characters are read as if by repeated calls to sbumpc()
. That is, if less than
characters are immediately available, the function calls uflow()
to provide more until Traits::eof()
Classes derived from
std::basic_streambuf are permitted to provide more efficient implementations of this function.
|| pointer to the beginning of a char_type array
|| maximum number of characters to write
 Return value
The number of characters successfully read. If it is less than
count the input sequence has reached the end.
The rule about "more efficient implementations" permits bulk I/O without intermediate buffering: that's how std::ifstream::read simply passes the pointer to the POSIX
read() system call in some implementations of iostreams
 See also
|| invokes xsputn() |
(public member function)