xref: /dragonfly/lib/libc/stdio/fgets.3 (revision 2dac8a3e)
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32.\"     @(#)fgets.3	8.1 (Berkeley) 6/4/93
33.\" $FreeBSD: src/lib/libc/stdio/fgets.3,v 1.22 2009/02/28 06:00:58 das Exp $
34.\"
35.Dd September 9, 2019
36.Dt FGETS 3
37.Os
38.Sh NAME
39.Nm fgets ,
40.Nm gets_s
41.Nd get a line from a stream
42.Sh LIBRARY
43.Lb libc
44.Sh SYNOPSIS
45.In stdio.h
46.Ft char *
47.Fn fgets "char * restrict str" "int size" "FILE * restrict stream"
48.Ft char *
49.Fn gets_s "char *str" "rsize_t size"
50.Sh DESCRIPTION
51The
52.Fn fgets
53function
54reads at most one less than the number of characters specified by
55.Fa size
56from the given
57.Fa stream
58and stores them in the string
59.Fa str .
60Reading stops when a newline character is found,
61at end-of-file or error.
62The newline, if any, is retained.
63If any characters are read and there is no error, a
64.Ql \e0
65character is appended to end the string.
66.Pp
67The
68.Fn gets_s
69function
70is equivalent to
71.Fn fgets
72with a
73.Fa stream
74of
75.Dv stdin ,
76except that the newline character (if any) is not stored in the string.
77.Sh RETURN VALUES
78Upon successful completion,
79.Fn fgets
80and
81.Fn gets_s
82return
83a pointer to the string.
84If end-of-file occurs before any characters are read,
85they return
86.Dv NULL
87and the buffer contents remain unchanged.
88If an error occurs,
89they return
90.Dv NULL
91and the buffer contents are indeterminate.
92The
93.Fn fgets
94and
95.Fn gets_s
96functions
97do not distinguish between end-of-file and error, and callers must use
98.Xr feof 3
99and
100.Xr ferror 3
101to determine which occurred.
102.Sh ERRORS
103.Bl -tag -width Er
104.It Bq Er EBADF
105The given
106.Fa stream
107is not a readable stream.
108.El
109.Pp
110The
111.Fn fgets
112function may also fail and set
113.Va errno
114for any of the errors specified for the routines
115.Xr fflush 3 ,
116.Xr fstat 2 ,
117.Xr read 2 ,
118or
119.Xr malloc 3 .
120.Pp
121The
122.Fn gets_s
123function may also fail and set
124.Va errno
125for any of the errors specified for the routine
126.Xr getchar 3 .
127.Sh SEE ALSO
128.Xr feof 3 ,
129.Xr ferror 3 ,
130.Xr fgetln 3 ,
131.Xr fgetws 3 ,
132.Xr getline 3
133.Sh STANDARDS
134The
135.Fn fgets
136function conforms to
137.St -isoC-99 .
138.Fn gets_s
139conforms to
140.St -isoC-2011
141K.3.7.4.1.
142