ClosedRange
An interval from a lower bound up to, and including, an upper bound.
@frozen struct ClosedRange<Bound> where Bound : Comparable
Overview
You create a ClosedRange
instance by using the closed range operator (...
).
let throughFive = 0...5
A ClosedRange
instance contains both its lower bound and its upper bound.
throughFive.contains(3)
// true
throughFive.contains(10)
// false
throughFive.contains(5)
// true
Because a closed range includes its upper bound, a closed range whose lower bound is equal to the upper bound contains that value. Therefore, a ClosedRange
instance cannot represent an empty range.
let zeroInclusive = 0...0
zeroInclusive.contains(0)
// true
zeroInclusive.isEmpty
// false
Using a Closed Range as a Collection of Consecutive Values
When a closed range uses integers as its lower and upper bounds, or any other type that conforms to the Strideable
protocol with an integer stride, you can use that range in a for
-in
loop or with any sequence or collection method. The elements of the range are the consecutive values from its lower bound up to, and including, its upper bound.
for n in 3...5 {
print(n)
}
// Prints "3"
// Prints "4"
// Prints "5"
Because floating-point types such as Float
and Double
are their own Stride
types, they cannot be used as the bounds of a countable range. If you need to iterate over consecutive floating-point values, see the stride(from:through:by:)
function.