Range

struct Range<T : ForwardIndexType>

A collection of consecutive discrete index values.

T is both the element type and the index type of the collection.

Like other collections, a range containing one element has an endIndex that is the successor of its startIndex; and an empty range has startIndex == endIndex.

Axiom: for any Range r, r[i] == i.

Therefore, if T has a maximal value, it can serve as an endIndex, but can never be contained in a Range<T>.

It also follows from the axiom above that (-99..<100)[0] == 0. To prevent confusion (because some expect the result to be -99), in a context where T is known to be an integer type, subscripting with T is a compile-time error:

// error: could not find an overload for 'subscript'...
println( Range<Int>(start:-99, end:100)[0] )

However, subscripting that range still works in a generic context:

func brackets<T:ForwardIndexType>(x: Range<T>, i: T) -> T {
  return x[i] // Just forward to subscript
}
println(brackets(Range<Int>(start:-99, end:100), 0)) // prints 0

Inheritance	`CollectionType, DebugPrintable, Equatable, Printable, Reflectable, SequenceType, _CollectionType, _SequenceType, _Sequence_Type` View Protocol Hierarchy →
Associated Types	`Index = T` A type that represents a valid position in the collection. Valid indices consist of the position of every element and a "past the end" position that's not valid for use as a subscript. `ArraySlice = Range<T>` `Generator = RangeGenerator<T>` A type whose instances can produce the elements of this sequence, in order. `Element = T` Type alias inferred. `Index = T` Type alias inferred. `SubSequence = Slice<Range<T>>` Type alias inferred.
Import	`import Swift`