std::basic_streambuf<CharT,Traits>::sgetn, std::basic_streambuf<CharT,Traits>::xsgetn
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std::streamsize sgetn( char_type* s, std::streamsize count );
(1)
protected:
virtual std::streamsize xsgetn( char_type* s, std::streamsize count );
(2)
virtual std::streamsize xsgetn( char_type* s, std::streamsize count );
1) Calls
xsgetn(s, count) of the most derived class.2) Reads
count characters 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 count characters are immediately available, the function calls uflow() to provide more until Traits::eof() is returned. Classes derived from
std::basic_streambuf are permitted to provide more efficient implementations of this function.Contents
[edit] Parameters
s
-
pointer to the beginning of a char_type array
count
-
maximum number of characters to read.
[edit] Return value
The number of characters successfully read. If it is less than count the input sequence has reached the end.
[edit] Notes
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
[edit] Example
This section is incomplete
Reason: no example
Reason: no example