Is it good practice to NULL a pointer after deleting it?

Question

I\'ll start out by saying, use smart pointers and you\'ll never have to worry about this.

What are the problems with the following code?

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Answer 1

Explicitly nulling after delete strongly suggests to a reader that the pointer represents something which is conceptually optional. If I saw that being done, I'd start worrying that everywhere in the source the pointer gets used that it should be first tested against NULL.

If that's what you actually mean, it's better to make that explicit in the source using something like boost::optional

optional p (new Foo);
// (use p.get(), but must test p for truth first!...)
delete p.get();
p = optional();

But if you really wanted people to know the pointer has "gone bad", I'll pitch in 100% agreement with those who say the best thing to do is make it go out of scope. Then you're using the compiler to prevent the possibility of bad dereferences at runtime.

That's the baby in all the C++ bathwater, shouldn't throw it out. :)