ungetc(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
   unsigned 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
   occurs 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
   attributes(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
   library  with  low-level  calls  to  read(2)  for  the  file descriptor
   associated 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 4.09 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/.

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