xref: /freebsd/lib/libc/stdio/fgetln.3 (revision b1f9167f94059fd55c630891d359bcff987bd7eb)
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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