The fgetwc() function shall obtain the next character (if present) from
the input stream pointed to by stream, convert that to the
corresponding wide-character code, and advance the associated file position
indicator for the stream (if defined).
If an error occurs, the resulting value of the file position indicator for the
stream is unspecified.
The fgetwc() function may mark the st_atime field of the file
associated with stream for update. The st_atime field shall be
marked for update by the first successful execution of fgetc(),
fgets(), fgetwc(), fgetws(), fread(),
fscanf(), getc(), getchar(), gets(), or
scanf() using stream that returns data not supplied by a prior
call to ungetc() or ungetwc().
Upon successful completion, the fgetwc() function shall return the
wide-character code of the character read from the input stream pointed to by
stream converted to a type wint_t. If the stream is at
end-of-file, the end-of-file indicator for the stream shall be set and
fgetwc() shall return WEOF. If a read error occurs, the error indicator
for the stream shall be set, fgetwc() shall return WEOF, and
shall set errno to indicate the error. If an encoding error occurs, the
error indicator for the stream shall be set, fgetwc() shall return
WEOF, and shall set errno to indicate the error.
The fgetwc() function shall fail if data needs to be read and:
The O_NONBLOCK flag is set for the file descriptor
underlying stream and the process would be delayed in the
The file descriptor underlying stream is not a valid
file descriptor open for reading.
The data obtained from the input stream does not form a
The read operation was terminated due to the receipt of a
signal, and no data was transferred.
A physical I/O error has occurred, or the process is in a
background process group attempting to read from its controlling terminal,
and either the process is ignoring or blocking the SIGTTIN signal or the
process group is orphaned. This error may also be generated for
The file is a regular file and an attempt was made to read
at or beyond the offset maximum associated with the corresponding stream.
The fgetwc() function may fail if:
Insufficient storage space is available.
A request was made of a nonexistent device, or the request
was outside the capabilities of the device.
Portions of this text are reprinted and reproduced in electronic form from IEEE
Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable
Operating System Interface (POSIX), The Open Group Base Specifications Issue
6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics
Engineers, Inc and The Open Group. In the event of any discrepancy between
this version and the original IEEE and The Open Group Standard, the original
IEEE and The Open Group Standard is the referee document. The original
Standard can be obtained online at http://www.opengroup.org/unix/online.html