Input and Output Functions

The stream classes std::istream and std::ostream are often used for the reading and writing of data. Use of std::istream classes requires the <istream> header; use of std::ostream classes requires the <ostream> header. You can have both with the header <iostream>. std::istream is a typedef for the class basic_istream and the character type char, std::ostream for the class basic_ostream respectively:

typedef basic_istream<char> istream;
typedef basic_ostream<char> ostream;

C++ has four predefined stream objects for the convenient dealing with the keyboard and the monitor.

The four predefined stream objects

Stream object	C pendant	Device	Buffered
std::cin	stdin	keyboard	yes
std::cout	stdout	monitor	yes
std::cerr	stderr	monitor	no
std::clog	&...