best way to return (char *)

[joe at gistdev.UUCP]

Here is a question I haven't seen recently, and I'd like to get opinions from
the collective wisdom of the group.  Suppose I am writing a function that is
going to construct a character string, and is going to return a pointer to
that string.  What is the best way to do this so that your pointer is sure
to be valid when used?  I have seen several approaches to this problem:

    .	Have the caller pass a (char *) and let the caller worry about
	allocating whatever space is needed.

    .	Have the routine malloc() space, and let the caller free() it when
	done with the returned pointer.

    .	Have the routine allocate the buffer pointed to by the returned
	(char *) as a static.

    .	Assume it's the caller's problem to strcpy() (or other such) from the
	pointer before something else can use the space.

    .	Don't worry about it at all -- nothing is going to trash your memory
	at the pointed-to address before you can actually use it.

I'm sure there are other approaches, but these were the ones I could think of
off the top of my head.  In general, how _should_ this be done to be safest?

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