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Message: [QUOTE="Old Wolf, post: 2439477"] I don't think there is any lying here; you are allowed to cast one object pointer type to another as long as there are no alignment issues. The troubles only (potentially) start when you dereference the pointer. &a[0] must be correctly aligned for int, because the members of a[0] are ints, and there cannot be any padding before the first member of an array. Here there could be alignment issues. But if there are not, then no UB if c is not dereferenced. (Note: I don't think I worded that exactly right -- the code always has UB, but on implementations where there were no alignment problems, the code would behave in a well-defined manner). Agree (int* you mean, not *int). IMHO, *b causes undefined behaviour iff i >= 3, because "a" (ie. &a[0]) points to an array of 3 ints, and a bounds checking implementation could flag this. But if b were initialized as: int *b = &a; then there would be no UB because &a points to an object that is the size of nine ints. But some people think that even as written there is no UB because a[0] is part of the entire object "a", I don't recall seeing any consensus when this point has been debated in the past. *c would cause undefined behaviour in most cases, because either the bytes pointed to by c form a trap representation for an int*, or if they form an address that isn't the address of a valid object. [/QUOTE]