News for hackers. Stuff that matters.

A comment on What Every C Programmer Should Know About Undefined Behavior (2011). Parent comment

Re:What Every C Programmer Should Know About Undefined Behav... by lmm on Thursday January 05, 2017 @09:58AM (#13327535)
> IIRC, simply making P point to anything other than an object or 1 past the end of an array is already UB.

I don't think this is true in the strict sense you're describing it. Certainly forming a null pointer isn't UB as I understand it, only dereferencing one.

[ Parent | on HN ]
Re:What Every C Programmer Should Know About Undefined Behav... by 0xcde4c3db on Thursday January 05, 2017 @10:28AM (#13327831)
Yes, NULL is another exception that I forgot. I'm not sure this is ever explicitly stated as a distinct rule in the standard, but it seems to be implied by various arithmetic and conversion operations on pointers being UB if the result doesn't point to a valid object.
[ Parent | on HN ]