ungetc

FGETC(3)                   Linux Programmer's Manual                  FGETC(3)

NAME
       fgetc, fgets, getc, getchar, ungetc - input of characters and strings

SYNOPSIS
       #include <stdio.h>

       int fgetc(FILE *stream);

       char *fgets(char *s, int size, FILE *stream);

       int getc(FILE *stream);

       int getchar(void);

       int ungetc(int c, FILE *stream);

DESCRIPTION
       fgetc()  reads  the next character from stream and returns it as an un-
       signed char cast to an int, or EOF on end of file or error.

       getc() is equivalent to fgetc() except that it may be implemented as  a
       macro which evaluates stream more than once.

       getchar() is equivalent to getc(stdin).

       fgets()  reads in at most one less than size characters from stream and
       stores them into the buffer pointed to by s.  Reading  stops  after  an
       EOF  or a newline.  If a newline is read, it is stored into the buffer.
       A terminating null byte ('\0') is stored after the  last  character  in
       the buffer.

       ungetc()  pushes  c  back to stream, cast to unsigned char, where it is
       available for subsequent read operations.  Pushed-back characters  will
       be returned in reverse order; only one pushback is guaranteed.

       Calls  to the functions described here can be mixed with each other and
       with calls to other input functions from the stdio library for the same
       input stream.

       For nonlocking counterparts, see unlocked_stdio(3).

RETURN VALUE
       fgetc(),  getc() and getchar() return the character read as an unsigned
       char cast to an int or EOF on end of file or error.

       fgets() returns s on success, and NULL on error or when end of file oc-
       curs while no characters have been read.

       ungetc() returns c on success, or EOF on error.

ATTRIBUTES
       For  an  explanation  of  the  terms  used  in  this  section,  see at-
       tributes(7).

       +--------------------------+---------------+---------+
       |Interface                 | Attribute     | Value   |
       +--------------------------+---------------+---------+
       |fgetc(), fgets(), getc(), | Thread safety | MT-Safe |
       |getchar(), ungetc()       |               |         |
       +--------------------------+---------------+---------+

CONFORMING TO
       POSIX.1-2001, POSIX.1-2008, C89, C99.

       It is not advisable to mix calls to input functions from the stdio  li-
       brary  with  low-level calls to read(2) for the file descriptor associ-
       ated with the input stream; the results  will  be  undefined  and  very
       probably not what you want.

SEE ALSO
       read(2), write(2), ferror(3), fgetwc(3), fgetws(3), fopen(3), fread(3),
       fseek(3),  getline(3),   gets(3),   getwchar(3),   puts(3),   scanf(3),
       ungetwc(3), unlocked_stdio(3), feature_test_macros(7)

COLOPHON
       This  page  is  part of release 5.05 of the Linux man-pages project.  A
       description of the project, information about reporting bugs,  and  the
       latest     version     of     this    page,    can    be    found    at
       https://www.kernel.org/doc/man-pages/.

GNU                               2017-09-15                          FGETC(3)