buffer -- Definition

A buffer is  a portion of memory set aside to  hold data read from or to be
written to  another process  or device.   Often, although not  always, this
involves setting  aside a portion of  the arena with malloc  or its related
functions.

Buffering, and  problems therewith, are  encountered most often  when using
the  standard input  and output (STDIO)  routines.  Many  operating systems
(including COHERENT) automatically place data from a peripheral device into
a buffer.   Buffers normally can be cleared with  fflush(), by pressing the
carriage return key on routines that perform input, or by sending a newline
character on  routines that perform  output.  The function  fclose(), which
closes  a file  stream, flushes  all buffers  associated with  that stream.
exit() calls fclose().

Combining unbuffered and buffered I/O  functions on the same file or device
within one program will produce results that are at best unpredictable.

Example

The following  example demonstrates what does and does  not happen when you
use fflush() with the output buffer.

#include <stdio.h>
main()
{
    extern char *malloc();
    char *buffer;

    /* use malloc() to create a 120-char buffer */
    if ((buffer = malloc(120)) == NULL) {
        /* if malloc() fails, bail out */
        fprintf(stderr, "malloc failed\n");
        exit(1);
    }

    printf("Type your name:  ");
    fflush(stdout);
    gets(buffer);
    printf("Your name is %s\n", buffer);
}

See Also

arena,
array,
close(),
exit(),
fflush(),
malloc(),
Programming COHERENT,
stdio.h

© 2012 by Stephen A. Ness