Re: Joy of this, Joy of that

On 23/11/2024 10:16, Richard Kettlewell wrote:

Lawrence D'Oliveiro <ldo@nz.invalid> writes:

On Sat, 23 Nov 2024 07:09:06 GMT, Charlie Gibbs wrote:

So it's the good old-fashioned way - free
each allocation one by one and hope you don't forget one.

>
One thing that helps is that free(3) is idempotent:

 It is not. Freeing the same non-null pointer twice is a bug (and a
common source of vulnerabilities).
 

calling it on a NULL pointer is a harmless no-op, so there is no need
to check for NULL before calling it. So my standard technique
(simplifying somewhat) is

 ‘free() and null out all copies of the pointer that can ever reach
free() in the future’ is idempotent, if you can get it right (which is
usually not too hard in a well-organized program).
 

I had to read that three times to understand what you said there.
A comma after the first free() would have helped.:-)
Otherwise +100
--
For every complex problem there is an answer that is clear, simple, and wrong.
H.L.Mencken