setbuffer(3S)           (BSD Compatibility Package)           setbuffer(3S)


   NAME
         setbuffer, setlinebuf - assign buffering to a stream

   SYNOPSIS
         cc [ flag... ] file ... -lucb

         #include <stdio.h>

         setbuffer(stream, buf, size)
         FILE *stream;
         char *buf;
         int size;

         setlinebuf(stream)
         FILE *stream;

   DESCRIPTION
         The three types of buffering available are unbuffered, block
         buffered, and line buffered.  When an output stream is unbuffered,
         information appears on the destination file or terminal as soon as
         written; when it is block buffered many characters are saved up and
         written as a block; when it is line buffered characters are saved up
         until a NEWLINE is encountered or input is read from any line
         buffered input stream.  fflush (see fclose(3S)) may be used to force
         the block out early.  Normally all files are block buffered.  A
         buffer is obtained from malloc(3C) upon the first getc or putc(3S) on
         the file.

         By default, output to a terminal is line buffered, except for output
         to the standard stream stderr which is unbuffered, and all other
         input/output is fully buffered.

         setbuffer can be used after a stream has been opened but before it is
         read or written.  It uses the character array buf whose size is
         determined by the size argument instead of an automatically allocated
         buffer.  If buf is the NULL pointer, input/output will be completely
         unbuffered.  A manifest constant BUFSIZ, defined in the <stdio.h>
         header file, tells how big an array is needed:

               char buf[BUFSIZ];

         setlinebuf is used to change the buffering on a stream from block
         buffered or unbuffered to line buffered.  Unlike setbuffer, it can be
         used at any time that the file descriptor is active.

         A file can be changed from unbuffered or line buffered to block
         buffered by using freopen (see fopen(3S)).  A file can be changed
         from block buffered or line buffered to unbuffered by using freopen
         followed by setbuffer with a buffer argument of NULL.




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   setbuffer(3S)           (BSD Compatibility Package)           setbuffer(3S)


   SEE ALSO
         setbuf(3S)

         fclose(3S), fopen(3S), fread(3S), getc(3S), malloc(3C), printf(3S),
         putc(3S), puts(3S), setbuf(3S) in the Programmer's Reference Manual.

   NOTE
         A common source of error is allocating buffer space as an automatic
         variable in a code block, and then failing to close the stream in the
         same block.











































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