[colanderman]

> I incorrectly thought that what I remembered about pointer arithmetic would apply here. 1 * sizeof(int) = 0x04, so I guessed 0x7fffdfbf7f04.

Your pointer arithmetic was correct. What you missed was that &x is a pointer to an array of five ints (so, sizeof(int[5])), not a single int.

I on the other hand didn't realize sizeof(int) is not necessarily 8 on 64-bit machines. You learn something new every day...

[scott_s]

On 64-bit machines, int is typically 4 bytes. Longs are typically 8 bytes. But if you really need to assume a certain length, use the typedefs from ctype.h. (For example, if you wanted a 4 byte signed integer, you would say int32_t. An 8 byte unsigned integer would be uint64_t.)