Synopsis
#include <stdio.h>
size_t fwrite(const void *restrict ptr, size_t size, size_t nitems,
FILE *restrict stream);
Status
Partially implemented
Conformance
IEEE Std 1003.1-2017
Description
The fwrite() function shall write, from the array pointed to by ptr, up to nitems elements whose size is
specified by size, to the stream pointed to by stream. For each object, size calls shall be made to the fputc() function, taking the values (in order) from an array of unsigned char
exactly overlaying the object. The file-position indicator for the stream (if defined) shall be advanced by the number of bytes
successfully written. If an error occurs, the resulting value of the file-position indicator for the stream is unspecified.
The
last data modification and last file status change timestamps of the file shall be marked for update between the successful
execution of fwrite() and the next successful completion of a call to fflush()
or fclose() on the same stream, or a call to exit() or abort().
Return value
The fwrite() function shall return the number of elements successfully written, which may be less than nitems if a write error is encountered. If size or nitems is 0, fwrite() shall return 0 and the state of the stream remains unchanged. Otherwise, if a write error occurs, the error indicator for the stream shall be set, and errno shall be set to indicate the error.
Errors
Refer to fputc.
Tests
Untested
Known bugs
None