getc, fgetc, getc_unlocked, getchar, getchar_unlocked,
getw - Get a byte or word from an input stream
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 standards as follows:
fgetc(), getc_unlocked, getc(), getchar(),
getchar_unlocked, getw(): XSH5.0
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 compile-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
[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() functions 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 funlockfile() 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 architecture 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 success of getw(). The getw() function assumes
no special alignment in the file.
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
The getc() and getchar() functions may be macros (depending
on the compile-time definitions used in the source).
Consequently, you cannot use these interfaces where a
function is necessary; for example, a subroutine 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
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 constant 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 error.
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
descriptor 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 orphaned.
A physical I/O error has occurred. (This condition
was defined for Issue 4 Version 2 and higher issues
of the XSH specification.) Insufficient memory is
available for the operation. The device associated
with stream does not exist.
Functions: flockfile(3), funlockfile(3), gets(3),
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