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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)

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setbuf(3s)																setbuf(3s)

Name
       setbuf, setbuffer, setlinebuf, setvbuf - assign buffering to a stream

Syntax
       #include <stdio.h>

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

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

       void setlinebuf(stream)
       FILE *stream;

       int setvbuf(stream, buf, type, size)
       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 new line is encountered or input is read from stdin.	The routine may be
       used to force the block out early.  Normally all files are block buffered.  For further information, see A buffer is obtained from upon the
       first  or  on  the  file.   If  the  standard stream stdout refers to a terminal it is line buffered.  The standard stream stderr is always
       unbuffered.

       The routine is used after a stream has been opened but before it is read or written.  The character array buf is used instead of  an  auto-
       matically  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];

       The routine, an alternate form of 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.

       The routine is used to change stdout or stderr from block buffered or unbuffered to line buffered.  Unlike and it can be used at  any  time
       that the file descriptor is active.

       The  routine  may  be  used  after a stream has been opened but before it is read or written.  Type determines how stream will be buffered.
       Legal values for type, defined in stdio.h are:

	_IOFBF	      causes input/output to be fully buffered.

	_IOLBF	      causes output to be line buffered; the buffer will be flushed when a new line is written, the buffer is full,  or  input	is
		      requested.

	_IONBF	      causes input/output to be completely unbuffered.

       If  buf is not the NULL pointer, the array it points to will be used for buffering, instead of an automatically allocated buffer.  The size
       specifies the size of the buffer to be used.  The constant BUFSIZ in <stdio.h> is suggested as a good  buffer  size.   If  input/output	is
       unbuffered, buf and size are ignored.

       By default, output to a terminal is line buffered and all other input/output is fully buffered.

       A  file	can be changed from unbuffered or line buffered to block buffered by using For further information, see A file can be changed from
       block buffered or line buffered to unbuffered by using followed by with a buffer argument of NULL.

Restrictions
       The standard error stream should be line buffered by default.

       The and functions are not portable to non 4.2 BSD versions of UNIX.

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

																	setbuf(3s)

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