xref: /freebsd/lib/libc/stdio/fgetln.3 (revision 4c8945a06b01a5c8122cdeb402af36bb46a06acc)
1.\" Copyright (c) 1990, 1991, 1993
2.\"	The Regents of the University of California.  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.\" 4. Neither the name of the University nor the names of its contributors
13.\"    may be used to endorse or promote products derived from this software
14.\"    without specific prior written permission.
15.\"
16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26.\" SUCH DAMAGE.
27.\"
28.\"     @(#)fgetln.3	8.3 (Berkeley) 4/19/94
29.\" $FreeBSD$
30.\"
31.Dd April 19, 1994
32.Dt FGETLN 3
33.Os
34.Sh NAME
35.Nm fgetln
36.Nd get a line from a stream
37.Sh LIBRARY
38.Lb libc
39.Sh SYNOPSIS
40.In stdio.h
41.Ft char *
42.Fn fgetln "FILE *stream" "size_t *len"
43.Sh DESCRIPTION
44The
45.Fn fgetln
46function
47returns a pointer to the next line from the stream referenced by
48.Fa stream .
49This line is
50.Em not
51a C string as it does not end with a terminating
52.Dv NUL
53character.
54The length of the line, including the final newline,
55is stored in the memory location to which
56.Fa len
57points.
58(Note, however, that if the line is the last
59in a file that does not end in a newline,
60the returned text will not contain a newline.)
61.Sh RETURN VALUES
62Upon successful completion a pointer is returned;
63this pointer becomes invalid after the next
64.Tn I/O
65operation on
66.Fa stream
67(whether successful or not)
68or as soon as the stream is closed.
69Otherwise,
70.Dv NULL
71is returned.
72The
73.Fn fgetln
74function
75does not distinguish between end-of-file and error; the routines
76.Xr feof 3
77and
78.Xr ferror 3
79must be used
80to determine which occurred.
81If an error occurs, the global variable
82.Va errno
83is set to indicate the error.
84The end-of-file condition is remembered, even on a terminal, and all
85subsequent attempts to read will return
86.Dv NULL
87until the condition is
88cleared with
89.Xr clearerr 3 .
90.Pp
91The text to which the returned pointer points may be modified,
92provided that no changes are made beyond the returned size.
93These changes are lost as soon as the pointer becomes invalid.
94.Sh ERRORS
95.Bl -tag -width Er
96.It Bq Er EBADF
97The argument
98.Fa stream
99is not a stream open for reading.
100.El
101.Pp
102The
103.Fn fgetln
104function
105may also fail and set
106.Va errno
107for any of the errors specified for the routines
108.Xr fflush 3 ,
109.Xr malloc 3 ,
110.Xr read 2 ,
111.Xr stat 2 ,
112or
113.Xr realloc 3 .
114.Sh SEE ALSO
115.Xr ferror 3 ,
116.Xr fgets 3 ,
117.Xr fgetwln 3 ,
118.Xr fopen 3 ,
119.Xr getline 3 ,
120.Xr putc 3
121.Sh HISTORY
122The
123.Fn fgetln
124function first appeared in
125.Bx 4.4 .
126