GETC(3S)							      GETC(3S)

NAME    [Toc]    [Back]

     getc, getchar, fgetc, getw, getc_unlocked,	getchar_unlocked - get
     character or word from a stream

SYNOPSIS    [Toc]    [Back]

     #include <stdio.h>

     int getc (FILE *stream);

     int getchar (void);

     int fgetc (FILE *stream);

     int getw (FILE *stream);

     int getc_unlocked (FILE *stream);

     int getchar_unlocked (void);

DESCRIPTION    [Toc]    [Back]

     Fgetc and getc return the next character (if it exists) from the named
     input stream, as an unsigned character converted to an integer.  It also
     moves the file pointer, if	defined, ahead one character in	stream.
     getchar is	defined	as getc(stdin).	 Each of getc,getchar and fgetc	exist
     as	functions in the C library. Getc and getchar are also available	as
     macros in <stdio.h> (see below under CAVEATS for important	details	on the
     implementation of these macros.)

     Getw returns the next word	(i.e., integer)	from the named input stream.
     Getw increments the associated file pointer, if defined, to point to the
     next integer-sized	word.  Getw assumes no special alignment in the	file.

     The getc_unlocked and getchar_unlocked functions are equivalent to	the
     getc and getchar functions, respectively.	However, these functions are
     not thread-safe and thus must only	be called under	the protection of the
     flockfile (or ftrylockfile) and funlockfile functions.

SEE ALSO    [Toc]    [Back]

     fclose(3S), ferror(3S), fopen(3S),	fread(3S), gets(3S), putc(3S),
     scanf(3S),	stdio(3S), ungetc(3S).

DIAGNOSTICS    [Toc]    [Back]

     These functions return the	constant EOF at	end-of-file or upon an error.
     Because EOF is a valid integer, it	is not sufficient to detect getw
     errors.  ferror(3S) must be used as well.

WARNING    [Toc]    [Back]

     If	the integer value returned by getc, getchar, or	fgetc is stored	into a
     character variable	and then compared against the integer constant EOF,
     the comparison may	never succeed, because sign-extension of a character
     on	widening to integer is machine-dependent.




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GETC(3S)							      GETC(3S)

CAVEATS    [Toc]    [Back]

     When using	the macro versions of getc and getchar,	the stream argument
     may be evaluated more than	once.  Thus, it	must not be an expression with
     side-effects.  In particular, getc(*f++) does not work sensibly.  In
     these situations, the macro must either be	#undef'd, or fgetc should be
     used instead.

     Because of	possible differences in	word length and	byte ordering, files
     written using putw	are machine-dependent, and may not be read using getw
     on	a different processor.

BUGS    [Toc]    [Back]

     When using	the macros for getc and	getchar, hidden	external names may be
     referenced. Although these	names are prefixed with	an underscore, they
     may conflict with names which the ANSI C Standard reserves	for the	user
     when appearing in a local context.	 It is thus recommended	that users of
     these macros reserve all names which begin	with an	underscore for the
     implementation, and avoid defining	such names, even in a local context.


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