```
const T& operator[](size_t n) const;
T& operator[](size_t n);
```

The expression addressof(a[i]) != addressof(b[j])
evaluates to true for any two arrays
a and b and for any
size_t i and size_t j
such that i < a.size()
and j < b.size().

[*Note 2*: *end note*]

This property indicates an absence of aliasing and can be used to
advantage by optimizing compilers.

Compilers can take advantage
of inlining, constant propagation, loop fusion,
tracking of pointers obtained from
operator new,
and other techniques to generate efficient
valarrays.

â€” The reference returned by the subscript operator for an array shall
be valid until the member function
resize(size_t, T) is called for that array or until the lifetime of
that array ends, whichever happens first.