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Annotation of 43BSDReno/lib/libc/stdio/setbuf.3, revision 1.1

1.1     ! root        1: .\" Copyright (c) 1980 Regents of the University of California.
        !             2: .\" All rights reserved.  The Berkeley software License Agreement
        !             3: .\" specifies the terms and conditions for redistribution.
        !             4: .\"
        !             5: .\"    @(#)setbuf.3    6.4 (Berkeley) 4/1/89
        !             6: .\"
        !             7: .TH SETBUF 3  "April 1, 1989"
        !             8: .UC 4
        !             9: .SH NAME
        !            10: setbuf, setbuffer, setlinebuf \- assign buffering to a stream
        !            11: .SH SYNOPSIS
        !            12: .B #include <stdio.h>
        !            13: .PP
        !            14: .B setbuf(stream, buf)
        !            15: .br
        !            16: .SM
        !            17: .B FILE
        !            18: .B *stream;
        !            19: .br
        !            20: .B char *buf;
        !            21: .PP
        !            22: .B setbuffer(stream, buf, size)
        !            23: .br
        !            24: .SM
        !            25: .B FILE
        !            26: .B *stream;
        !            27: .br
        !            28: .B char *buf;
        !            29: .br
        !            30: .B int size;
        !            31: .PP
        !            32: .B setlinebuf(stream)
        !            33: .br
        !            34: .SM
        !            35: .B FILE
        !            36: .B *stream;
        !            37: .SH DESCRIPTION
        !            38: The three types of buffering available are unbuffered, block buffered,
        !            39: and line buffered.
        !            40: When an output stream is unbuffered, information appears on the
        !            41: destination file or terminal as soon as written;
        !            42: when it is block buffered many characters are saved up and written as a block;
        !            43: when it is line buffered characters are saved up until a newline is
        !            44: encountered or input is read from stdin.
        !            45: .I Fflush
        !            46: (see 
        !            47: .IR fclose (3))
        !            48: may be used to force the block out early.
        !            49: Normally all files are block buffered.
        !            50: A buffer is obtained from
        !            51: .IR  malloc (3)
        !            52: upon the first
        !            53: .I getc
        !            54: or
        !            55: .IR  putc (3)
        !            56: on the file.
        !            57: If the standard stream
        !            58: .B stdout
        !            59: refers to a terminal it is line buffered.
        !            60: The standard stream
        !            61: .B stderr
        !            62: is always unbuffered.
        !            63: .PP
        !            64: .I Setbuf
        !            65: is used after a stream has been opened but before it is read or written.
        !            66: The character array
        !            67: .I buf
        !            68: is used instead of an automatically allocated buffer.  If
        !            69: .I buf
        !            70: is the constant pointer
        !            71: .SM
        !            72: .B NULL,
        !            73: input/output will be completely unbuffered.
        !            74: A manifest constant 
        !            75: .SM
        !            76: .B BUFSIZ
        !            77: tells how big an array is needed:
        !            78: .IP
        !            79: .B char
        !            80: buf[BUFSIZ];
        !            81: .PP
        !            82: .IR Setbuffer ,
        !            83: an alternate form of 
        !            84: .IR setbuf ,
        !            85: is used after a stream has been opened but before it is read or written.
        !            86: The character array
        !            87: .I buf
        !            88: whose size is determined by the 
        !            89: .I size
        !            90: argument is used instead of an automatically allocated buffer.  If
        !            91: .I buf
        !            92: is the constant pointer
        !            93: .SM
        !            94: .BR NULL ,
        !            95: input/output will be completely unbuffered.
        !            96: .PP
        !            97: .I Setlinebuf
        !            98: is used to change
        !            99: .I stdout
        !           100: or
        !           101: .I stderr
        !           102: from block buffered or unbuffered to line buffered.
        !           103: Unlike
        !           104: .I setbuf
        !           105: and
        !           106: .I setbuffer
        !           107: it can be used at any time that the file descriptor is active.
        !           108: .PP
        !           109: A file can be changed from unbuffered or line buffered to block buffered
        !           110: by using
        !           111: .I freopen
        !           112: (see
        !           113: .IR fopen (3)).
        !           114: A file can be changed from block buffered or line buffered to unbuffered
        !           115: by using
        !           116: .I freopen
        !           117: followed by
        !           118: .I setbuf
        !           119: with a buffer argument of 
        !           120: .SM
        !           121: .BR NULL .
        !           122: .SH "SEE ALSO"
        !           123: fopen(3),
        !           124: getc(3),
        !           125: putc(3),
        !           126: malloc(3),
        !           127: fclose(3),
        !           128: puts(3),
        !           129: printf(3),
        !           130: fread(3)
        !           131: .SH BUGS
        !           132: The
        !           133: .I setbuffer
        !           134: and
        !           135: .I setlinebuf
        !           136: functions are not portable to non-4.2BSD versions of UNIX.
        !           137: On 4.2BSD and 4.3BSD systems,
        !           138: .I setbuf
        !           139: always uses a suboptimal buffer size and should be avoided.
        !           140: .I Setbuffer
        !           141: is not usually needed
        !           142: as the default file I/O buffer sizes are optimal.

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