setbuffer(3s) [bsd man page]

SETBUF(3S)																SETBUF(3S)

NAME

       setbuf, setbuffer, setlinebuf - assign buffering to a stream

SYNOPSIS

       #include <stdio.h>

       setbuf(stream, buf)
       FILE *stream;
       char *buf;

       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 stdin.  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(3) upon the
       first getc or putc(3S) on the file.  If the standard stream stdout refers to a terminal it is line buffered.  The standard stream stderr is
       always unbuffered.

       Setbuf is used after a stream has been opened but before it is read or written.	The character array buf is used instead  of  an  automati-
       cally allocated buffer.	If buf is the constant pointer NULL, input/output will be completely unbuffered.  A manifest constant BUFSIZ tells
       how big an array is needed:

	      char buf[BUFSIZ];

       Setbuffer, an alternate form of setbuf, is used after a stream has been opened but before it is read or written.  The character	array  buf
       whose  size  is determined by the size argument is used instead of an automatically allocated buffer.  If buf is the constant pointer NULL,
       input/output will be completely unbuffered.

       Setlinebuf is used to change stdout or stderr from block buffered or unbuffered to line buffered.  Unlike setbuf and 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 setbuf with a buffer argument of NULL.

SEE ALSO

       fopen(3S), getc(3S), putc(3S), malloc(3), fclose(3S), puts(3S), printf(3S), fread(3S)

BUGS

       The standard error stream should be line buffered by default.

       The setbuffer and setlinebuf functions are not portable to non-4.2BSD versions of UNIX.	On 4.2BSD and 4.3BSD systems, setbuf always uses a
       suboptimal buffer size and should be avoided.  Setbuffer is not usually needed as the default file I/O buffer sizes are optimal.

4th Berkeley Distribution					   May 12, 1986 							SETBUF(3S)

Check Out this Related Man Page

SETBUF(3)						     Library Functions Manual							 SETBUF(3)

NAME

       setbuf, setvbuf - assign buffering to a stream

SYNOPSIS

       #include <stdio.h>

       int setbuf(FILE *stream, char *buf)
       int setvbuf(FILE *stream, char *buf, int type, size_t size)

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 stdin.  Fflush (see fclose(3))
       may be used to force the block out early.  Normally all files are block buffered.  A buffer is obtained from malloc(3) upon the first  getc
       or  putc(3)  on	the  file.   If the standard stream stdout refers to a terminal it is line buffered.  The standard stream stderr is always
       unbuffered.

       Setbuf is used after a stream has been opened but before it is read or written.	The character array buf is used instead  of  an  automati-
       cally allocated buffer.	If buf is the constant pointer NULL, input/output will be completely unbuffered.  A manifest constant BUFSIZ tells
       how big an array is needed:

	      char buf[BUFSIZ];

       Setvbuf, an alternate form of setbuf, is used after a stream has been opened but before it is read or written.  It has three uses,  depend-
       ing on the value of the type argument:

       setvbuf(stream, buf, _IOFBF, size)
	    Causes  input/output  to be fully buffered using the character array buf whose size is determined by the size argument.  If buf is the
	    constant pointer NULL, then an automatically allocated buffer will be used.

       setvbuf(stream, buf, _IOLBF, size)
	    Like above, except that output will be line buffered, i.e. the buffer will be flushed when a newline is written, the buffer  is  full,
	    or input is requested.

       setvbuf(stream, buf, _IONBF, size)
	    Causes input/output to be completely unbuffered.  Buf and size are ignored.

       A  file	can  be  changed  between unbuffered, line buffered, or block buffered by using freopen (see fopen(3)) followed by the appropriate
       setvbuf call.

SEE ALSO

       fopen(3), getc(3), putc(3), malloc(3), fclose(3), puts(3), printf(3), fread(3).

4th Berkeley Distribution					   May 12, 1986 							 SETBUF(3)

Linux and UNIX Man Pages

setbuffer(3s) [bsd man page]

Check Out this Related Man Page