ISO/IEC 9899:2011 6.5.8 - 5

gistfile1.txt

When two pointers are compared, the result depends on the relative locations in the
address space of the objects pointed to. If two pointers to object types both point to the
same object, or both point one past the last element of the same array object, they
compare equal. If the objects pointed to are members of the same aggregate object,
pointers to structure members declared later compare greater than pointers to members
declared earlier in the structure, and pointers to array elements with larger subscript
values compare greater than pointers to elements of the same array with lower subscript
values. All pointers to members of the same union object compare equal. If the
expression P points to an element of an array object and the expression Q points to the
last element of the same array object, the pointer expression Q+1 compares greater than
P. In all other cases, the behavior is undefined.