[unix-history] / lib / libc / stdio / stdio.3

.\" Copyright (c) 1990, 1991 Regents of the University of California.
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\" 1. Redistributions of source code must retain the above copyright
.\"    notice, this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\"    notice, this list of conditions and the following disclaimer in the
.\"    documentation and/or other materials provided with the distribution.
.\" 3. All advertising materials mentioning features or use of this software
.\"    must display the following acknowledgement:
.\"	This product includes software developed by the University of
.\"	California, Berkeley and its contributors.
.\" 4. Neither the name of the University nor the names of its contributors
.\"    may be used to endorse or promote products derived from this software
.\"    without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
.\" SUCH DAMAGE.
.\"
.\"     @(#)stdio.3	6.5 (Berkeley) 5/6/91
.\"
.Dd May 6, 1991
.Dt STDIO 3
.Os BSD 4
.Sh NAME
.Nm stdio
.Nd standard input/output library functions
.Sh SYNOPSIS
.Fd #include <stdio.h>
.Fd FILE *stdin;
.Fd FILE *stdout;
.Fd FILE *stderr;
.Sh DESCRIPTION
The standard
.Tn I/O
library provides a simple and efficient buffered stream
.Tn I/O
interface.
Input and ouput is mapped into logical data streams
and the physical
.Tn I/O
characteristics are concealed. The functions and macros are listed
below; more information is available from the individual man pages.
.Pp
A stream is associated with an external file (which may be a physical
device) by
.Em opening
a file, which may involve creating a new file. Creating an
existing file causes its former contents to be discarded.
If a file can support positioning requests (such as a disk file, as opposed
to a terminal) then a
.Em file position indicator
associated with the stream is positioned at the start of the file (byte
zero), unless the file is opened with appened mode. If append mode
is used, the position indicator will be placed the end-of-file.
The position indicator is maintained by subsequent reads, writes
and positioning requests. All input occurs as if the characters
were read by successive calls to the
.Xr fgetc 3
function; all ouput takes place as if all characters were
read by successive calls to the
.Xr fputc 3
function.
.Pp
A file is disassociated from a stream by
.Em closing
the file.
Ouput streams are flushed (any unwritten buffer contents are transferred
to the host environment) before the stream is disassociated from the file.
The value of a pointer to a
.Dv FILE
object is indeterminate after a file is closed (garbage).
.Pp
A file may be subsequently reopened, by the same or another program
execution, and its contents reclaimed or modified (if it can be repositioned
at the start).  If the main function returns to its original caller, or
the
.Xr exit 3
function is called, all open files are closed (hence all output
streams are flushed) before program termination.  Other methods
of program termination, such as
.Xr abort 3
do not bother about closing files properly.
.Pp
At program startup, three text streams are predefined and need not be
opened explicitly
\(em
.Em standard input 
(for reading converntional input),
\(em
.Em standard output 
(for writing converntional input),
and
.Em standard error
(for writing diagnostic output).
These streams are abbreviated
.Em stdin , stdout
and
.Em stderr .
When opened, the standard error stream
is not fully buffered; the standard input and output streams are
fully buffered if and only if the streams do not to refer to
an interactive device.
.Pp
Output streams that refer to terminal devices
are always line buffered by default;
pending output to such streams is written automatically
whenever an input stream that refers to a terminal device is read.
In cases where a large amount of computation is done after printing
part of a line on an output terminal, it is necessary to
.Xr fflush 3
the standard output before going off and computing so that the output
will appear.
.Pp
The
.Nm stdio
library is a part of the library
.Xr libc
and routines are automatically loaded as needed by the compilers
.Xr cc 1
and
.Xr pc 1 .
The
.Tn SYNOPSIS
sections of the following manual pages indicate which include files
are to be used, what the compiler declaration for the function
looks like and which external variables are of interest.
.Pp
The following are defined as macros;
these names may not be re-used
without first removing their current definitions with
.Dv #undef :
.Dv BUFSIZ ,
.Dv EOF ,
.Dv FILENAME_MAX ,
.DV FOPEN_MAX ,
.Dv L_cuserid ,
.Dv L_ctermid ,
.Dv L_tmpnam,
.Dv NULL ,
.Dv SEEK_END ,
.Dv SEEK_SET ,
.Dv SEE_CUR ,
.Dv TMP_MAX ,
.Dv clearerr ,
.Dv feof ,
.Dv ferror ,
.Dv fileno ,
.Dv fropen ,
.Dv fwopen ,
.Dv getc ,
.Dv getchar ,
.Dv putc ,
.Dv putchar ,
.Dv stderr ,
.Dv stdin ,
.Dv stdout .
Function versions of the macro functions
.Xr feof ,
.Xr ferror ,
.Xr clearerr ,
.Xr fileno ,
.Xr getc ,
.Xr getchar ,
.Xr putc ,
and
.Xr putchar
exist and will be used if the macros
definitions are explicitly removed.
.Sh SEE ALSO
.Xr open 2 ,
.Xr close 2 ,
.Xr read 2 ,
.Xr write 2
.Sh BUGS
The standard buffered functions do not interact well with certain other
library and system functions, especially
.Xr vfork
and
.Xr abort .
.Sh STANDARDS
The
.Nm stdio
library conforms to
.St -ansiC .
.Sh LIST OF FUNCTIONS
.Bl -column "Description"
.Sy Function	Description
clearerr	check and reset stream status
fclose	close a stream
fdopen	stream open functions
feof	check and reset stream status
ferror	check and reset stream status
fflush	flush a stream
fgetc	get next character or word from input stream
fgetline	get a line from a stream
fgetpos	reposition a stream
fgets	get a line from a stream
fileno	check and reset stream status
fopen	stream open functions
fprintf	formatted output conversion
fpurge	flush a stream
fputc	output a character or word to a stream
fputs	output a line to a stream
fread	binary stream input/output
freopen	stream open functions
fropen	open a stream
fscanf	input format conversion
fseek	reposition a stream
fsetpos	reposition a stream
ftell	reposition a stream
funopen	open a stream
fwopen	open a stream
fwrite	binary stream input/output
getc	get next character or word from input stream
getchar	get next character or word from input stream
gets	get a line from a stream
getw	get next character or word from input stream
mktemp	make temporary file name (unique)
perror	system error messages
printf	formatted output conversion
putc	output a character or word to a stream
putchar	output a character or word to a stream
puts	output a line to a stream
putw	output a character or word to a stream
remove	remove directory entry
rewind	reposition a stream
scanf	input format conversion
setbuf	stream buffering operations
setbuffer	stream buffering operations
setlinebuf	stream buffering operations
setvbuf	stream buffering operations
snprintf	formatted output conversion
sprintf	formatted output conversion
sscanf	input format conversion
strerror	system error messages
sys_errlist	system error messages
sys_nerr	system error messages
tempnam	temporary file routines
tmpfile	temporary file routines
tmpnam	temporary file routines
ungetc	un-get character from input stream
vfprintf	formatted output conversion
vfscanf	input format conversion
vprintf	formatted output conversion
vscanf	input format conversion
vsnprintf	formatted output conversion
vsprintf	formatted output conversion
vsscanf	input format conversion
.El
Commit	Line	Data
15637ed4 RG	1	.\" Copyright (c) 1990, 1991 Regents of the University of California.
	2	.\" All rights reserved.
	3	.\"
	4	.\" Redistribution and use in source and binary forms, with or without
	5	.\" modification, are permitted provided that the following conditions
	6	.\" are met:
	7	.\" 1. Redistributions of source code must retain the above copyright
	8	.\" notice, this list of conditions and the following disclaimer.
	9	.\" 2. Redistributions in binary form must reproduce the above copyright
	10	.\" notice, this list of conditions and the following disclaimer in the
	11	.\" documentation and/or other materials provided with the distribution.
	12	.\" 3. All advertising materials mentioning features or use of this software
	13	.\" must display the following acknowledgement:
	14	.\" This product includes software developed by the University of
	15	.\" California, Berkeley and its contributors.
	16	.\" 4. Neither the name of the University nor the names of its contributors
	17	.\" may be used to endorse or promote products derived from this software
	18	.\" without specific prior written permission.
	19	.\"
	20	.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	21	.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	22	.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	23	.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	24	.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	25	.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	26	.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	27	.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	28	.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	29	.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	30	.\" SUCH DAMAGE.
	31	.\"
	32	.\" @(#)stdio.3 6.5 (Berkeley) 5/6/91
	33	.\"
	34	.Dd May 6, 1991
	35	.Dt STDIO 3
	36	.Os BSD 4
	37	.Sh NAME
	38	.Nm stdio
	39	.Nd standard input/output library functions
	40	.Sh SYNOPSIS
	41	.Fd #include <stdio.h>
	42	.Fd FILE *stdin;
	43	.Fd FILE *stdout;
	44	.Fd FILE *stderr;
	45	.Sh DESCRIPTION
	46	The standard
	47	.Tn I/O
	48	library provides a simple and efficient buffered stream
	49	.Tn I/O
	50	interface.
	51	Input and ouput is mapped into logical data streams
	52	and the physical
	53	.Tn I/O
	54	characteristics are concealed. The functions and macros are listed
	55	below; more information is available from the individual man pages.
	56	.Pp
	57	A stream is associated with an external file (which may be a physical
	58	device) by
	59	.Em opening
	60	a file, which may involve creating a new file. Creating an
	61	existing file causes its former contents to be discarded.
	62	If a file can support positioning requests (such as a disk file, as opposed
	63	to a terminal) then a
	64	.Em file position indicator
65	associated with the stream is positioned at the start of the file (byte
66	zero), unless the file is opened with appened mode. If append mode
67	is used, the position indicator will be placed the end-of-file.
68	The position indicator is maintained by subsequent reads, writes
69	and positioning requests. All input occurs as if the characters
70	were read by successive calls to the
71	.Xr fgetc 3
72	function; all ouput takes place as if all characters were
73	read by successive calls to the
74	.Xr fputc 3
75	function.
76	.Pp
77	A file is disassociated from a stream by
78	.Em closing
79	the file.
c2714ef5	80	Ouput streams are flushed (any unwritten buffer contents are transferred
15637ed4 RG	81	to the host environment) before the stream is disassociated from the file.
	82	The value of a pointer to a
	83	.Dv FILE
	84	object is indeterminate after a file is closed (garbage).
	85	.Pp
	86	A file may be subsequently reopened, by the same or another program
	87	execution, and its contents reclaimed or modified (if it can be repositioned
	88	at the start). If the main function returns to its original caller, or
	89	the
	90	.Xr exit 3
	91	function is called, all open files are closed (hence all output
	92	streams are flushed) before program termination. Other methods
	93	of program termination, such as
	94	.Xr abort 3
	95	do not bother about closing files properly.
	96	.Pp
	97	At program startup, three text streams are predefined and need not be
	98	opened explicitly
	99	\(em
	100	.Em standard input
	101	(for reading converntional input),
	102	\(em
	103	.Em standard output
	104	(for writing converntional input),
	105	and
	106	.Em standard error
	107	(for writing diagnostic output).
	108	These streams are abbreviated
	109	.Em stdin , stdout
	110	and
	111	.Em stderr .
	112	When opened, the standard error stream
	113	is not fully buffered; the standard input and output streams are
	114	fully buffered if and only if the streams do not to refer to
	115	an interactive device.
	116	.Pp
	117	Output streams that refer to terminal devices
	118	are always line buffered by default;
	119	pending output to such streams is written automatically
	120	whenever an input stream that refers to a terminal device is read.
	121	In cases where a large amount of computation is done after printing
	122	part of a line on an output terminal, it is necessary to
	123	.Xr fflush 3
	124	the standard output before going off and computing so that the output
	125	will appear.
	126	.Pp
	127	The
	128	.Nm stdio
	129	library is a part of the library
	130	.Xr libc
	131	and routines are automatically loaded as needed by the compilers
	132	.Xr cc 1
	133	and
	134	.Xr pc 1 .
	135	The
	136	.Tn SYNOPSIS
	137	sections of the following manual pages indicate which include files
	138	are to be used, what the compiler declaration for the function
	139	looks like and which external variables are of interest.
	140	.Pp
	141	The following are defined as macros;
	142	these names may not be re-used
	143	without first removing their current definitions with
	144	.Dv #undef :
145	.Dv BUFSIZ ,
146	.Dv EOF ,
147	.Dv FILENAME_MAX ,
148	.DV FOPEN_MAX ,
149	.Dv L_cuserid ,
150	.Dv L_ctermid ,
151	.Dv L_tmpnam,
152	.Dv NULL ,
153	.Dv SEEK_END ,
154	.Dv SEEK_SET ,
155	.Dv SEE_CUR ,
156	.Dv TMP_MAX ,
157	.Dv clearerr ,
158	.Dv feof ,
159	.Dv ferror ,
160	.Dv fileno ,
161	.Dv fropen ,
162	.Dv fwopen ,
163	.Dv getc ,
164	.Dv getchar ,
165	.Dv putc ,
166	.Dv putchar ,
167	.Dv stderr ,
168	.Dv stdin ,
169	.Dv stdout .
170	Function versions of the macro functions
171	.Xr feof ,
172	.Xr ferror ,
173	.Xr clearerr ,
174	.Xr fileno ,
175	.Xr getc ,
176	.Xr getchar ,
177	.Xr putc ,
178	and
179	.Xr putchar
180	exist and will be used if the macros
181	definitions are explicitly removed.
182	.Sh SEE ALSO
183	.Xr open 2 ,
184	.Xr close 2 ,
185	.Xr read 2 ,
186	.Xr write 2
187	.Sh BUGS
188	The standard buffered functions do not interact well with certain other
189	library and system functions, especially
190	.Xr vfork
191	and
192	.Xr abort .
193	.Sh STANDARDS
194	The
195	.Nm stdio
196	library conforms to
197	.St -ansiC .
198	.Sh LIST OF FUNCTIONS
199	.Bl -column "Description"
200	.Sy Function Description
201	clearerr check and reset stream status
202	fclose close a stream
203	fdopen stream open functions
204	feof check and reset stream status
205	ferror check and reset stream status
206	fflush flush a stream
207	fgetc get next character or word from input stream
208	fgetline get a line from a stream
209	fgetpos reposition a stream
210	fgets get a line from a stream
211	fileno check and reset stream status
212	fopen stream open functions
213	fprintf formatted output conversion
214	fpurge flush a stream
215	fputc output a character or word to a stream
216	fputs output a line to a stream
217	fread binary stream input/output
218	freopen stream open functions
219	fropen open a stream
220	fscanf input format conversion
221	fseek reposition a stream
222	fsetpos reposition a stream
223	ftell reposition a stream
224	funopen open a stream
225	fwopen open a stream
226	fwrite binary stream input/output
227	getc get next character or word from input stream
228	getchar get next character or word from input stream
229	gets get a line from a stream
230	getw get next character or word from input stream
231	mktemp make temporary file name (unique)
232	perror system error messages
233	printf formatted output conversion
234	putc output a character or word to a stream
235	putchar output a character or word to a stream
236	puts output a line to a stream
237	putw output a character or word to a stream
238	remove remove directory entry
239	rewind reposition a stream
240	scanf input format conversion
241	setbuf stream buffering operations
242	setbuffer stream buffering operations
243	setlinebuf stream buffering operations
244	setvbuf stream buffering operations
245	snprintf formatted output conversion
246	sprintf formatted output conversion
247	sscanf input format conversion
248	strerror system error messages
249	sys_errlist system error messages
250	sys_nerr system error messages
251	tempnam temporary file routines
252	tmpfile temporary file routines
253	tmpnam temporary file routines
254	ungetc un-get character from input stream
255	vfprintf formatted output conversion
256	vfscanf input format conversion
257	vprintf formatted output conversion
258	vscanf input format conversion
259	vsnprintf formatted output conversion
260	vsprintf formatted output conversion
261	vsscanf input format conversion
262	.El