Random Access Range

A range X where boost::range_iterator<X>::type is a model of Random Access Traversal Iterator.

Name	Expression	Return type
Size of range	`boost::size(a)`	`boost::range_size<X>::type`

Expression	Semantics	Postcondition
`boost::size(a)`	Returns the size of the Range, that is, its number of elements. Note `boost::size(a) == 0u` is equivalent to `boost::empty(a)`.	`boost::size(a) >= 0`

boost::size(a) completes in amortized constant time.

Range size	`boost::size(a)` is equal to the `boost::end(a)` - `boost::begin(a)`.