c - Why is my function representation not reverse-copying data? -

c - Why is my function representation not reverse-copying data? -

i have function representation of fwrite write bytes backwards. however.. doesn't re-create them backwards appears strange.

size_t fwrite_backward ( const void * ptr, size_t size, size_t count, file * stream ) { int i, chr; for(i = count * size; != 0; i--) { if( fputc(*(unsigned char*)ptr + (count * size) - i, stream) != eof ) chr++; } homecoming chr; }

it supposed behave fwrite 2 differences:

it copies info backwards it doesn't set ferror

what might doing wrong?

the implementation below seems work. corrects minor design flaws of version:

your code writes out bytes backwards, should write items backwards bytes in items in original order. (after all, what's distinction between size , count for?) code below works items of size.

yor code returns number of bytes written. fwrite returns number of items written.

the loop ends on unsuccessful writes.

so:

size_t fwrite_rev(const void *ptr, size_t size, size_t count, file *stream) { const unsigned char *p = ptr; size_t written = 0; while (count--) { if (fwrite(p + size * count, size, 1, stream) < 1) break; written++; } homecoming written; }

c io fwrite