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'\" t
.\" Copyright, the authors of the Linux man-pages project
.\"
.\" SPDX-License-Identifier: Linux-man-pages-copyleft
.\"
.TH fgetc 3 2025-10-10 "Linux man-pages (unreleased)"
.SH NAME
fgetc, fgets, 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 );
.B "int getchar(void);"
.P
.BR "char *fgets(" "int size;"
.BI " 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 getchar ()
is equivalent to
.IR fgetc(stdin) .
.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]\[rs]0\[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 ()
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 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)
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