FPUTWC(3C) Standard C Library Functions FPUTWC(3C)


fputwc, putwc, putwchar - put wide-character code on a stream


#include <stdio.h>
#include <wchar.h>

wint_t fputwc(wchar_t wc, FILE*stream);

wint_t putwc(wchar_t wc, FILE*stream);

#include <wchar.h>

wint_t putwchar(wchar_t wc);


The fputwc() function writes the character corresponding to the wide-
character code wc to the output stream pointed to by stream, at the
position indicated by the associated file-position indicator for the
stream (if defined), and advances the indicator appropriately. If the
file cannot support positioning requests, or if the stream was opened
with append mode, the character is appended to the output stream. If an
error occurs while writing the character, the shift state of the output
file is left in an undefined state.

The st_ctime and st_mtime fields of the file will be marked for update
between the successful execution of fputwc() and the next successful
completion of a call to fflush(3C) or fclose(3C) on the same stream or a
call to exit(2) or abort(3C).

The putwc() function is equivalent to fputwc(), except that it is
implemented as a macro.

The call putwchar(wc) is equivalent to putwc(wc, stdout). The putwchar()
routine is implemented as a macro.


Upon successful completion, fputwc(), putwc(), and putwchar() return wc.
Otherwise, they return WEOF, the error indicator for the stream is set,
and errno is set to indicate the error.


The fputwc(), putwc(), and putwchar() functions will fail if either the
stream is unbuffered or data in the stream's buffer needs to be written,

The O_NONBLOCK flag is set for the file descriptor underlying
stream and the process would be delayed in the write operation.

The file descriptor underlying stream is not a valid file
descriptor open for writing.

An attempt was made to write to a file that exceeds the maximum
file size or the process's file size limit; or the file is a
regular file and an attempt was made to write at or beyond the
offset maximum associated with the corresponding stream.

The write 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 a member
of a background process group attempting to write to its
controlling terminal, TOSTOP is set, the process is neither
ignoring nor blocking SIGTTOU, and the process group of the
process is orphaned. stream was created by open_wmemstream(3C)
and a wide-character or byte sequence buffered is invalid in
the current locale.

There was no free space remaining on the device containing the

An attempt is made to write to a pipe or FIFO that is not open
for reading by any process. A SIGPIPE signal will also be sent
to the calling thread.

The fputwc(), putwc(), and putwchar() functions may fail if:

Insufficient storage space is available.

A request was made of a non-existent device, or the request was
outside the capabilities of the device.

The wide-character code wc does not correspond to a valid


Functions exist for the putwc() and putwchar() macros. To get the
function form, the macro name must be undefined (for example, #undef

When the macro form is used, putwc() evaluates the stream argument more
than once. In particular, putwc(wc, *f++) does not work sensibly. The
fputwc() function should be used instead when evaluating the stream
argument has side effects.


See attributes(7) for descriptions of the following attributes:

|Interface Stability | Standard |
|MT-Level | MT-Safe |


exit(2), ulimit(2), abort(3C), fclose(3C), ferror(3C), fflush(3C),
fopen(3C), setbuf(3C), attributes(7), standards(7)

March 25, 2020 FPUTWC(3C)