summaryrefslogtreecommitdiffstats
path: root/man/man3/fgetc.3
blob: 03937120c81a60ebe5bdd2c8f9640b5c6f06febf (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
'\" t
.\" Copyright (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de)
.\"
.\" SPDX-License-Identifier: Linux-man-pages-copyleft
.\"
.\" Modified Wed Jul 28 11:12:07 1993 by Rik Faith (faith@cs.unc.edu)
.\" Modified Fri Sep  8 15:48:13 1995 by Andries Brouwer (aeb@cwi.nl)
.TH fgetc 3 2024-05-02 "Linux man-pages (unreleased)"
.SH NAME
fgetc, fgets, getc, getchar, ungetc \- input of characters and strings
.SH LIBRARY
Standard C library
.RI ( libc ", " \-lc )
.SH SYNOPSIS
.nf
.B #include <stdio.h>
.P
.BI "int fgetc(FILE *" stream );
.BI "int getc(FILE *" stream );
.B "int getchar(void);"
.P
.BI "char *fgets(char " s "[restrict ." size "], int " size ", \
FILE *restrict " stream );
.P
.BI "int ungetc(int " c ", FILE *" stream );
.fi
.SH DESCRIPTION
.BR fgetc ()
reads the next character from
.I stream
and returns it as an
.I unsigned char
cast to an
.IR int ,
or
.B EOF
on end of file or error.
.P
.BR getc ()
is equivalent to
.BR fgetc ()
except that it may be implemented as a macro which evaluates
.I stream
more than once.
.P
.BR getchar ()
is equivalent to
.BI "getc(" stdin ) \fR.
.P
.BR fgets ()
reads in at most one less than
.I size
characters from
.I stream
and stores them into the buffer pointed to by
.IR s .
Reading stops after an
.B EOF
or a newline.
If a newline is read, it is stored into the buffer.
A terminating null byte (\[aq]\e0\[aq])
is stored after the last character in the buffer.
.P
.BR ungetc ()
pushes
.I c
back to
.IR stream ,
cast to
.IR "unsigned char" ,
where it is available for subsequent read operations.
Pushed-back characters
will be returned in reverse order; only one pushback is guaranteed.
.P
Calls to the functions described here can be mixed with each other and with
calls to other input functions from the
.I stdio
library for the same input stream.
.P
For nonlocking counterparts, see
.BR unlocked_stdio (3).
.SH RETURN VALUE
.BR fgetc (),
.BR getc (),
and
.BR getchar ()
return the character read as an
.I unsigned char
cast to an
.I int
or
.B EOF
on end of file or error.
.P
.BR fgets ()
returns
.I s
on success, and NULL
on error or when end of file occurs while no characters have been read.
.P
.BR ungetc ()
returns
.I c
on success, or
.B EOF
on error.
.SH ATTRIBUTES
For an explanation of the terms used in this section, see
.BR attributes (7).
.TS
allbox;
lbx lb lb
l l l.
Interface	Attribute	Value
T{
.na
.nh
.BR fgetc (),
.BR fgets (),
.BR getc (),
.BR getchar (),
.BR ungetc ()
T}	Thread safety	MT-Safe
.TE
.SH STANDARDS
C11, POSIX.1-2008.
.SH HISTORY
POSIX.1-2001, C89.
.SH NOTES
It is not advisable to mix calls to input functions from the
.I stdio
library with low-level calls to
.BR read (2)
for the file descriptor associated with the input stream; the results
will be undefined and very probably not what you want.
.SH SEE ALSO
.BR read (2),
.BR write (2),
.BR ferror (3),
.BR fgetwc (3),
.BR fgetws (3),
.BR fopen (3),
.BR fread (3),
.BR fseek (3),
.BR getline (3),
.BR gets (3),
.BR getwchar (3),
.BR puts (3),
.BR scanf (3),
.BR ungetwc (3),
.BR unlocked_stdio (3),
.BR feature_test_macros (7)