B.1 Input and Output:

The input and output functions, types, and macros defined in <stdio.h> represent nearly one third of the library. A stream is a source or destination of data that may be associated with a disk or other peripheral. The library supports text streams and binary streams, although on some systems, notably UNIX, these are identical. A text stream is a sequence of lines; each line has zero or more characters and is terminated by 'n'. An environment may need to convert a text stream to or from some other representation (such as mapping 'n' to carriage return and linefeed). A binary stream is a sequence of unprocessed bytes that record internal data, with the property that if it is written, then read back on the same system, it will compare equal. A stream is connected to a file or device by opening it; the connection is broken by closing the stream. Opening a file returns a pointer to an object of type FILE, which records whatever information is necessary to control the stream. We will use ``file pointer'' and ``stream'' interchangeably when there is no ambiguity. When a program begins execution, the three streams stdin, stdout, and stderr are already open.