prototype

size_t fwrite(const void *ptr, size_t size, size_t nelem, FILE *stream);

The function writes characters to the output stream stream, accessing values from successive elements of the array whose first element has the address (char *)ptr until the function writes size*nelem characters or sets the error indicator. It returns n/size, where n is the number of characters it wrote. If the function sets the error indicator, the file-position indicator is indeterminate.