| .\" Copyright (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de) |
| .\" |
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| .\" Since the Linux kernel and libraries are constantly changing, this |
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| .\" 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 2021-03-22 "GNU" "Linux Programmer's Manual" |
| .SH NAME |
| fgetc, fgets, getc, getchar, ungetc \- input of characters and strings |
| .SH SYNOPSIS |
| .nf |
| .B #include <stdio.h> |
| .PP |
| .BI "int fgetc(FILE *" stream ); |
| .BI "int getc(FILE *" stream ); |
| .B "int getchar(void);" |
| .PP |
| .BI "char *fgets(char *restrict " s ", int " size ", FILE *restrict " stream ); |
| .PP |
| .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 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. |
| .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 fgets () |
| returns |
| .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 ATTRIBUTES |
| For an explanation of the terms used in this section, see |
| .BR attributes (7). |
| .ad l |
| .nh |
| .TS |
| allbox; |
| lbx lb lb |
| l l l. |
| Interface Attribute Value |
| T{ |
| .BR fgetc (), |
| .BR fgets (), |
| .BR getc (), |
| .BR getchar (), |
| .BR ungetc () |
| T} Thread safety MT-Safe |
| .TE |
| .hy |
| .ad |
| .sp 1 |
| .SH CONFORMING TO |
| POSIX.1-2001, POSIX.1-2008, C89, C99. |
| .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 gets (3), |
| .BR getwchar (3), |
| .BR puts (3), |
| .BR scanf (3), |
| .BR ungetwc (3), |
| .BR unlocked_stdio (3), |
| .BR feature_test_macros (7) |