stdiostream

Stdiostream refers to the standard C++ library facility that provides combined input and output functionality for character streams. In the C++ standard library, the type std::iostream is defined as a typedef for std::basic_iostream<char> and is declared in the header <iostream>. The class template basic_iostream<char> inherits from both basic_istream<char> and basic_ostream<char>, enabling both extraction (operator>>) and insertion (operator<<) operations on a single object.

The standard library defines specific objects for common I/O tasks, including std::cin (input), std::cout (output), std::cerr (unbuffered error output), and std::clog (buffered error logging). std::iostream itself is typically not instantiated directly by programmers; it serves as a common type that represents streams capable of both reading and writing, and it can be used in template code or to define user-defined dual-direction streams.

Usage and behavior: std::iostream supports standard stream operations, state bits via std::ios_base (good, fail, eof, bad), and locale and formatting control through std::ios and std::locale. It provides rdbuf() to access the underlying stream buffer and tie() to control flushing of tied streams. Like other iostream types, it adheres to the overall iostream formatting and error-handling semantics of the C++ standard library.

Performance considerations: Performance can be influenced by synchronization with the C stdio library (via std::ios::sync_with_stdio) and by buffering strategies. Disabling synchronization or adjusting buffering is a common approach to optimize I/O-intensive code, though it may affect compatibility with C I/O.

See also: std::basic_iostream, std::istream, std::ostream, std::cin, std::cout.