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.\" Copyright (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de)
.\"
.\" Permission is granted to make and distribute verbatim copies of this
.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\"
.\" Permission is granted to copy and distribute modified versions of this
.\" manual under the conditions for verbatim copying, provided that the
.\" entire resulting derived work is distributed under the terms of a
.\" permission notice identical to this one.
.\"
.\" Since the Linux kernel and libraries are constantly changing, this
.\" manual page may be incorrect or out-of-date. The author(s) assume no
.\" responsibility for errors or omissions, or for damages resulting from
.\" the use of the information contained herein. The author(s) may not
.\" have taken the same level of care in the production of this manual,
.\" which is licensed free of charge, as they might when working
.\" professionally.
.\"
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
.\" License.
.\" 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 GETS 3 2008-08-06 "GNU" "Linux Programmer's Manual"
.SH NAME
fgetc, fgets, getc, getchar, gets, ungetc \- input of characters and strings
.SH SYNOPSIS
.nf
.B #include <stdio.h>
.sp
.BI "int fgetc(FILE *" stream );
.BI "char *fgets(char *" "s" ", int " "size" ", FILE *" "stream" );
.BI "int getc(FILE *" stream );
.B "int getchar(void);"
.BI "char *gets(char *" "s" );
.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.
.PP
.BR getc ()
is equivalent to
.BR fgetc ()
except that it may be implemented as a macro which evaluates
.I stream
more than once.
.PP
.BR getchar ()
is equivalent to
.BI "getc(" stdin ) \fR.
.PP
.BR gets ()
reads a line from
.I stdin
into the buffer pointed to by
.I s
until either a terminating newline or
.BR EOF ,
which it replaces with
.BR \(aq\e0\(aq .
No check for buffer overrun is performed (see BUGS below).
.PP
.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
.B \(aq\e0\(aq
is stored after the last character in the buffer.
.PP
.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.
.PP
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.
.PP
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.
.PP
.BR gets ()
and
.BR fgets ()
return
.I s
on success, and NULL
on error or when end of file occurs while no characters have been read.
.PP
.BR ungetc ()
returns
.I c
on success, or
.B EOF
on error.
.SH "CONFORMING TO"
C89, C99, POSIX.1-2001.
LSB deprecates
.BR gets ().
POSIX.1-2008 removes the specification of
.BR gets ().
.SH BUGS
Never use
.BR gets ().
Because it is impossible to tell without knowing the data in advance how many
characters
.BR gets ()
will read, and because
.BR gets ()
will continue to store characters past the end of the buffer,
it is extremely dangerous to use.
It has been used to break computer security.
Use
.BR fgets ()
instead.
.PP
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 getwchar (3),
.BR puts (3),
.BR scanf (3),
.BR ungetwc (3),
.BR unlocked_stdio (3)
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