mirror of https://github.com/mkerrisk/man-pages
168 lines
3.9 KiB
Groff
168 lines
3.9 KiB
Groff
.\" Copyright (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de)
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.\"
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.\" %%%LICENSE_START(VERBATIM)
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.\" Permission is granted to make and distribute verbatim copies of this
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.\" manual provided the copyright notice and this permission notice are
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.\" preserved on all copies.
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.\"
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.\" Permission is granted to copy and distribute modified versions of this
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.\" manual under the conditions for verbatim copying, provided that the
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.\" entire resulting derived work is distributed under the terms of a
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.\" permission notice identical to this one.
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.\"
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.\" responsibility for errors or omissions, or for damages resulting from
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.\" the use of the information contained herein. The author(s) may not
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.\" have taken the same level of care in the production of this manual,
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.\" which is licensed free of charge, as they might when working
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.\" professionally.
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.\"
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" the source, must acknowledge the copyright and authors of this work.
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.\" %%%LICENSE_END
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.\"
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.\" Modified Wed Jul 28 11:12:07 1993 by Rik Faith (faith@cs.unc.edu)
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.\" Modified Fri Sep 8 15:48:13 1995 by Andries Brouwer (aeb@cwi.nl)
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.TH FGETC 3 2015-03-02 "GNU" "Linux Programmer's Manual"
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.SH NAME
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fgetc, fgets, getc, getchar, ungetc \- input of characters and strings
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.SH SYNOPSIS
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.nf
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.B #include <stdio.h>
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.sp
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.BI "int fgetc(FILE *" stream );
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.BI "char *fgets(char *" "s" ", int " "size" ", FILE *" "stream" );
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.BI "int getc(FILE *" stream );
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.B "int getchar(void);"
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.BI "int ungetc(int " c ", FILE *" stream );
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.fi
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.SH DESCRIPTION
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.BR fgetc ()
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reads the next character from
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.I stream
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and returns it as an
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.I unsigned char
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cast to an
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.IR int ,
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or
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.B EOF
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on end of file or error.
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.PP
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.BR getc ()
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is equivalent to
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.BR fgetc ()
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except that it may be implemented as a macro which evaluates
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.I stream
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more than once.
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.PP
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.BR getchar ()
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is equivalent to
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.BI "getc(" stdin ) \fR.
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.PP
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.BR fgets ()
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reads in at most one less than
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.I size
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characters from
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.I stream
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and stores them into the buffer pointed to by
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.IR s .
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Reading stops after an
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.B EOF
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or a newline.
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If a newline is read, it is stored into the buffer.
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A terminating null byte (\(aq\e0\(aq)
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is stored after the last character in the buffer.
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.PP
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.BR ungetc ()
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pushes
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.I c
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back to
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.IR stream ,
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cast to
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.IR "unsigned char" ,
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where it is available for subsequent read operations.
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Pushed-back characters
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will be returned in reverse order; only one pushback is guaranteed.
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.PP
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Calls to the functions described here can be mixed with each other and with
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calls to other input functions from the
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.I stdio
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library for the same input stream.
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.PP
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For nonlocking counterparts, see
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.BR unlocked_stdio (3).
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.SH RETURN VALUE
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.BR fgetc (),
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.BR getc ()
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and
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.BR getchar ()
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return the character read as an
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.I unsigned char
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cast to an
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.I int
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or
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.B EOF
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on end of file or error.
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.PP
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.BR fgets ()
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returns
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.I s
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on success, and NULL
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on error or when end of file occurs while no characters have been read.
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.PP
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.BR ungetc ()
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returns
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.I c
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on success, or
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.B EOF
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on error.
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.SH ATTRIBUTES
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For an explanation of the terms used in this section, see
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.BR attributes (7).
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.TS
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allbox;
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lbw25 lb lb
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l l l.
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Interface Attribute Value
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T{
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.BR fgetc (),
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.BR fgets (),
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.BR getc (),
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.br
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.BR getchar (),
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.BR ungetc ()
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T} Thread safety MT-Safe
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.TE
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.SH CONFORMING TO
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C89, C99, POSIX.1-2001.
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It is not advisable to mix calls to input functions from the
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.I stdio
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library with low-level calls to
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.BR read (2)
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for the file descriptor associated with the input stream; the results
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will be undefined and very probably not what you want.
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.SH SEE ALSO
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.BR read (2),
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.BR write (2),
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.BR ferror (3),
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.BR fgetwc (3),
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.BR fgetws (3),
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.BR fopen (3),
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.BR fread (3),
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.BR fseek (3),
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.BR getline (3),
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.BR gets (3),
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.BR getwchar (3),
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.BR puts (3),
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.BR scanf (3),
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.BR ungetwc (3),
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.BR unlocked_stdio (3),
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.BR feature_test_macros (7)
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