C s Predefined Streams

The Basic Stream Classes

The old-style iostream library uses the header file iostream.h. This file defines the foundational class hierarchy that supports I/O operations. If you will be performing file I/O, then you will need to also include fstream.h. To use array-based I/O, you will need to include strstrea.h.

The lowest-level class is called streambuf. This class provides the basic input and output operations. It is used primarily as a base class for other classes. Unless you are deriving your own I/O classes, you will not use streambuf directly.

The class ios is the base of the class hierarchy that you will typically use when using the C++ I/O system. It provides formatting, error checking, and status information. From ios are derived several classes—sometimes through intermediary classes. The classes derived either directly or indirectly from ios that you will typically use are listed here:

Class	Purpose
istream	General input
ostream	General output
iostream	General input/output
ifstream	File input
ofstream	File output
fstream	File input/output
istrstream	Array-based input
ostrstream	Array-based output
strstream	Array-based input/output