What is pointer variable range?

The range of a pointer variable is the range of addressable memory. For a 32-bit system there are 2^32 addresses ranging from 0x0 to 0xffffffff. Address 0x0 is a reserved address and is used to indicate a pointer refers to no object in particular (points to null).

Depending on the Word-alignment requirements of the architecture, certain addresses may be deemed invalid for a given type. For instance, a 4-byte integer is generally faster to access if it is aligned upon a 4-byte boundary.