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getc(3)								       getc(3)

       getc,  fgetc,  getc_unlocked,  getchar,	getchar_unlocked, getw - Get a
       byte or word from an input stream

       #include <stdio.h>

       int getc(
	       FILE *stream ); int fgetc(
	       FILE *stream ); int getc_unlocked(
	       FILE *stream ); int getchar(
	       void ); int getchar_unlocked(
	       void ); int getw(
	       FILE *stream );

       Standard C Library (libc)

       Interfaces documented on this reference page conform to industry	 stan‐
       dards as follows:

       fgetc(),	 getc_unlocked,	 getc(),  getchar(), getchar_unlocked, getw():

       Refer to the standards(5) reference page	 for  more  information	 about
       industry standards and associated tags.

       Points to the file structure of an open file.

       The  getc()  function returns the next byte from the input specified by
       the stream parameter and moves the file pointer, if defined, ahead  one
       byte  in	 stream. The getc() function may be a macro (depending on com‐
       pile-time definitions).	See the NOTES section for more information.

       The fgetc() function performs the same function as getc().

       The getchar() function returns the next byte from stdin,	 the  standard
       input stream. Note that getchar() can also be a macro.

       [Tru64  UNIX]  The reentrant versions of these functions are all locked
       against multiple threads calling them simultaneously. This  will	 incur
       an overhead to ensure integrity of the stream. The unlocked versions of
       these calls, getc_unlocked() and	 getchar_unlocked()  may  be  used  to
       avoid  the  overhead.  The getc_unlocked() and getchar_unlocked() func‐
       tions are functionally identical to the getc() and getchar() functions,
       except  that  getc_unlocked() and getchar_unlocked() may be safely used
       only within a scope that is protected by the flockfile()	 and  funlock‐
       file()  functions  used	as  a  pair.   The caller must ensure that the
       stream is locked before	these  functions  are  used.  The  getc()  and
       getchar() functions can also be macros.

       The getw() function reads the next word (int) from the stream. The size
       of a word is the size of an int, which may vary from one machine archi‐
       tecture to another. The getw() function returns the constant EOF at the
       end of the file or when an error occurs. Since EOF is a	valid  integer
       value,  the feof() and ferror() functions can be used to check the suc‐
       cess of getw(). The getw() function assumes no special alignment in the

       Because	of  possible  differences in int length and byte ordering from
       one machine architecture to another, files  written  using  the	putw()
       subroutine  are	machine dependent and may not be readable using getw()
       on a different type of processor.

       The getc() and getchar() functions may be macros (depending on the com‐
       pile-time  definitions  used  in the source).  Consequently, you cannot
       use these interfaces where a function is necessary; for example, a sub‐
       routine	pointer cannot point to one of these interfaces.  In addition,
       getc() does not work correctly with a stream parameter  that  has  side
       effects. In particular, the following does not work:


       In cases like this one, use the fgetc() function instead.

       Upon  successful completion, these functions and macros return the next
       byte or word from the input stream. If the stream  is  at  end-of-file,
       the  end-of-file	 indicator  for the stream is set and the integer con‐
       stant EOF is returned. If a read error occurs, the error indicator  for
       the  stream  is	set, EOF is returned, and errno is set to indicate the

       Because the EOF return is used to signal both a	successful  completion
       and  an	error  (accompanied  by errno), it is incumbent on the user to
       clear any pre-existing errno values before invoking these functions.

       The fgetc(), getc(),  getc_unlocked(),  getchar(),  getchar_unlocked(),
       and getw() functions set errno to the specified value for the following
       conditions: The O_NONBLOCK option is set for the underlying stream  and
       the  process would be delayed by the read operation.  The file descrip‐
       tor underlying the stream is not a valid file descriptor or is not open
       for  reading.  The read operation was interrupted by a signal which was
       caught and no data was transferred.  The call  is  attempting  to  read
       from  the  process's  controlling  terminal  and	 either the process is
       ignoring or blocking  the  SIGTTIN  signal  or  the  process  group  is

	      A	 physical  I/O error has occurred. (This condition was defined
	      for Issue 4 Version 2 and higher issues of  the  XSH  specifica‐
	      tion.)  Insufficient memory is available for the operation.  The
	      device associated with stream does not exist.

       Functions: flockfile(3), funlockfile(3), gets(3), getwc(3), putc(3)

       Standards: standards(5)


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