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Trail: Essential Classes
Lesson: Basic I/O
Basic I/O
I/O Streams
Byte Streams
Character Streams
Buffered Streams
Scanning and Formatting
Scanning
Formatting
I/O from the Command Line
Data Streams
Object Streams
File I/O
File Objects
Random Access Files
The New I/O Packages
Summary
Questions and Exercises
Home Page > Essential Classes > Basic I/O
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I/O Streams

> An I/O Stream represents an input source or an output destination. A stream can represent many different kinds of sources and destinations, including disk files, devices, other programs, and memory arrays.

> Streams support many different kinds of data, including simple bytes, primitive data types, localized characters, and objects. Some streams simply pass on data; others manipulate and transform the data in useful ways.

> No matter how they work internally, all streams present the same simple model to programs that use them: A stream is a sequence of data. A program uses an input stream to read data from a source, one item at a time:

> Reading information into a program.

> A program uses an output stream to write data to a destination, one item at time:

> Writing information from a program.

> In this lesson, we'll see streams that can handle all kinds of data, from primitive values to advanced objects.

> The data source and data destination pictured above can be anything that holds, generates, or consumes data. Obviously this includes disk files, but a source or destination can also another program, a peripheral device, a network socket, or an array.

> In the next section, we'll use the most basic kind of streams, byte streams, to demonstrate the common operations of Stream I/O. For sample input, we'll use the example file `xanadu.txt`, which contains the following verse:

> >     In Xanadu did Kubla Khan
> >     A stately pleasure-dome decree:
> >     Where Alph, the sacred river, ran
> >     Through caverns measureless to man
> >     Down to a sunless sea.

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