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[QUOTE="Richard Heathfield, post: 2470759"]
Your Uncle said:

No, I didn't. I did, however, post some shuffling pseudocode and source, 
just a few days ago, which was not taken from TAOCP.

I find that surprising. I'd have thought Dan Pop would have more sense.

That's fine as far as it goes, provided tmp exists and is of the appropriate 
type.

That's ghastly, but I can see what you're doing. Presumably this bit works 
fine, so let's move on.

"I explained two functions with file scope", according to Babelfish.

"They do that exactly resemble, however first with chars and the latters 
with ints. How do these functions become one?"

It can be made to work.

I doubt whether it's either your idea or Erich Fruehstueck's.

Incidentally, this isn't really permuting. It's shuffling.

Here is a generic swapping function:

void swap(void *s, void *t, size_t len)
{
  unsigned char *u = s;
  unsigned char *v = t;
  unsigned char tmp;
  while(len--)
  {
    tmp = *u;
    *u++ = *v;
    *v++ = tmp;
  }
}

Here is a generic shuffling function:

void shuffle(void *s, size_t size, size_t len)
{
  unsigned char *t = s;
  unsigned char *u = s;
  size_t i = 0;
  size_t r = 0;
  for(i = 0; i < len; i++)
  {
    r = (len - i) * rand() / (RAND_MAX + 1.0);
    swap(t + size * i, u + size * r, size);
  }
}
[/QUOTE]

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