Arrays are a separate data type than pointers, although in many contexts you can use an array where a pointer is expected and it will work, and this feature is

Arrays are a separate data type than pointers, although in many contexts you can use an array where a pointer is expected and it will work, and this feature is useful. Bounds-checking can sometimes be useful, and can perhaps have a switch to control its working. Some instruction sets (such as Flex) have tagged memory. In Flex, a pointer contains the address of a block (and a pointer can also be designated is read-only, disallowing writing through the pointer). There is also a "reference" consisting of a pointer and a displacement; I suppose this "reference" can be used to implement C pointers. If you use this, then the computer will automatically do bounds-checking and will result in an error if you make an access that is out of bounds. Tagged memory also allows to easily find the pointers in memory without needing to know the types of variables, which can be helpful for some uses, e.g. to detect improper use of realloc/free. Furthermore, null pointer can be zero (without the tag bits), which is automatically an error when used as a pointer because it is not a pointer.