Re: how to replace a substring in a string using C?

Netocrat wrote:

> > size_t count;

> > count = q - p;
>
> As discussed elsethread,
> under C99 this invokes undefined behaviour when q - p > PTRDIFF_MAX.
> I vaguely recall discussions on the semantics under
> C89, but can't recall the conclusion. Also under C99 count would be
> better declared ptrdiff_t but it appears that you're writing to C89.

Whether or not to declare count ptrdiff_t,
is not really an 89 vs 99 issue.
The type of the expression, (q - p), is ptrdiff_t.
If there's going to be undefined behavior,
it's going to be from that expression.

While there is no PTRDIFF_MAX macro in C89,
there is still a maximum limit to the ptrdiff_t type,
there's just no portable way to tell what is.
I suppose you can assume that it's at least 127.

--
pete
.

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