Generic Structure

ClosedRange

An interval from a lower bound up to, and including, an upper bound.

Declaration

@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.

Topics

Creating a Range

Create a new range using the closed range operator (...).

static func ... (Self, Self) -> ClosedRange<Self>

Returns a closed range that contains both of its bounds.

Converting Ranges

func relative<C>(to: C) -> Range<Bound>

Returns the range of indices described by this range expression within the given collection.

init(Range<Bound>)

Creates an instance equivalent to the given Range.

Inspecting a Range

var isEmpty: Bool

A Boolean value indicating whether the range contains no elements.

var count: Int

The number of elements in the collection.

let lowerBound: Bound

The range’s lower bound.

let upperBound: Bound

The range’s upper bound.

Checking for Containment

func contains(Bound) -> Bool

Returns a Boolean value indicating whether the given element is contained within the range.

func contains(where: (Bound) -> Bool) -> Bool

Returns a Boolean value indicating whether the sequence contains an element that satisfies the given predicate.

func allSatisfy((Bound) -> Bool) -> Bool

Returns a Boolean value indicating whether every element of a sequence satisfies a given predicate.

Clamping a Range

func clamped(to: ClosedRange<Bound>) -> ClosedRange<Bound>

Returns a copy of this range clamped to the given limiting range.

Accessing Elements

var first: Bound?

The first element of the collection.

var last: Bound?

The last element of the collection.

subscript(ClosedRange<Bound>.Index) -> Bound

Accesses the element at specified position.

subscript(Range<ClosedRange<Bound>.Index>) -> Slice<ClosedRange<Bound>>

Accesses a contiguous subrange of the collection’s elements.

subscript<R>(R) -> Slice<ClosedRange<Bound>>

Accesses the contiguous subrange of the collection’s elements specified by a range expression.

subscript((UnboundedRange_) -> ()) -> Slice<ClosedRange<Bound>>
subscript(Range<ClosedRange<Bound>.Index>) -> Slice<ClosedRange<Bound>>

Accesses a contiguous subrange of the collection’s elements.

func randomElement() -> Bound?

Returns a random element of the collection.

func randomElement<T>(using: inout T) -> Bound?

Returns a random element of the collection, using the given generator as a source for randomness.

Finding Elements

func first(where: (Bound) -> Bool) -> Bound?

Returns the first element of the sequence that satisfies the given predicate.

func firstIndex(of: Bound) -> ClosedRange<Bound>.Index?

Returns the first index where the specified value appears in the collection.

func firstIndex(where: (Bound) -> Bool) -> ClosedRange<Bound>.Index?

Returns the first index in which an element of the collection satisfies the given predicate.

func last(where: (Bound) -> Bool) -> Bound?

Returns the last element of the sequence that satisfies the given predicate.

func lastIndex(of: Bound) -> ClosedRange<Bound>.Index?

Returns the last index where the specified value appears in the collection.

func lastIndex(where: (Bound) -> Bool) -> ClosedRange<Bound>.Index?

Returns the index of the last element in the collection that matches the given predicate.

func min() -> Bound?

Returns the minimum element in the sequence.

func min(by: (Bound, Bound) -> Bool) -> Bound?

Returns the minimum element in the sequence, using the given predicate as the comparison between elements.

func max() -> Bound?

Returns the maximum element in the sequence.

func max(by: (Bound, Bound) -> Bool) -> Bound?

Returns the maximum element in the sequence, using the given predicate as the comparison between elements.

Selecting Elements

func filter((Bound) -> Bool) -> [Bound]

Returns an array containing, in order, the elements of the sequence that satisfy the given predicate.

func prefix(Int) -> Slice<ClosedRange<Bound>>

Returns a subsequence, up to the specified maximum length, containing the initial elements of the collection.

func prefix(through: ClosedRange<Bound>.Index) -> Slice<ClosedRange<Bound>>

Returns a subsequence from the start of the collection through the specified position.

func prefix(upTo: ClosedRange<Bound>.Index) -> Slice<ClosedRange<Bound>>

Returns a subsequence from the start of the collection up to, but not including, the specified position.

func prefix(while: (Bound) -> Bool) -> Slice<ClosedRange<Bound>>

Returns a subsequence containing the initial elements until predicate returns false and skipping the remaining elements.

func suffix(Int) -> Slice<ClosedRange<Bound>>

Returns a subsequence, up to the given maximum length, containing the final elements of the collection.

func suffix(from: ClosedRange<Bound>.Index) -> Slice<ClosedRange<Bound>>

Returns a subsequence from the specified position to the end of the collection.

Excluding Elements

func drop(while: (Bound) -> Bool) -> Slice<ClosedRange<Bound>>

Returns a subsequence by skipping elements while predicate returns true and returning the remaining elements.

func dropFirst(Int) -> Slice<ClosedRange<Bound>>

Returns a subsequence containing all but the given number of initial elements.

func dropLast(Int) -> Slice<ClosedRange<Bound>>

Returns a subsequence containing all but the specified number of final elements.

Tranforming a Range's Elements

func map<T>((Bound) -> T) -> [T]

Returns an array containing the results of mapping the given closure over the sequence’s elements.

func compactMap<ElementOfResult>((Bound) -> ElementOfResult?) -> [ElementOfResult]

Returns an array containing the non-nil results of calling the given transformation with each element of this sequence.

func flatMap<SegmentOfResult>((Bound) -> SegmentOfResult) -> [SegmentOfResult.Element]

Returns an array containing the concatenated results of calling the given transformation with each element of this sequence.

func flatMap<ElementOfResult>((Bound) -> ElementOfResult?) -> [ElementOfResult]
Deprecated
func reduce<Result>(Result, (Result, Bound) -> Result) -> Result

Returns the result of combining the elements of the sequence using the given closure.

func reduce<Result>(into: Result, (inout Result, Bound) -> ()) -> Result

Returns the result of combining the elements of the sequence using the given closure.

var lazy: LazySequence<ClosedRange<Bound>>

A sequence containing the same elements as this sequence, but on which some operations, such as map and filter, are implemented lazily.

Iterating Over a Range's Elements

func forEach((Bound) -> Void)

Calls the given closure on each element in the sequence in the same order as a for-in loop.

func enumerated() -> EnumeratedSequence<ClosedRange<Bound>>

Returns a sequence of pairs (n, x), where n represents a consecutive integer starting at zero and x represents an element of the sequence.

func makeIterator() -> IndexingIterator<ClosedRange<Bound>>

Returns an iterator over the elements of the collection.

var underestimatedCount: Int

A value less than or equal to the number of elements in the sequence, calculated nondestructively.

var underestimatedCount: Int

A value less than or equal to the number of elements in the collection.

Reordering Elements

func sorted() -> [Bound]

Returns the elements of the sequence, sorted.

func sorted(by: (Bound, Bound) -> Bool) -> [Bound]

Returns the elements of the sequence, sorted using the given predicate as the comparison between elements.

func reversed() -> ReversedCollection<ClosedRange<Bound>>

Returns a view presenting the elements of the collection in reverse order.

func shuffled() -> [Bound]

Returns the elements of the sequence, shuffled.

func shuffled<T>(using: inout T) -> [Bound]

Returns the elements of the sequence, shuffled using the given generator as a source for randomness.

Splitting and Joining Elements

func joined() -> FlattenSequence<ClosedRange<Bound>>

Returns the elements of this sequence of sequences, concatenated.

func joined<Separator>(separator: Separator) -> JoinedSequence<ClosedRange<Bound>>

Returns the concatenated elements of this sequence of sequences, inserting the given separator between each element.

func joined(separator: String) -> String

Returns a new string by concatenating the elements of the sequence, adding the given separator between each element.

func joined(separator: String) -> String

Returns a new string by concatenating the elements of the sequence, adding the given separator between each element.

func split(maxSplits: Int, omittingEmptySubsequences: Bool, whereSeparator: (Bound) -> Bool) -> [Slice<ClosedRange<Bound>>]

Returns the longest possible subsequences of the collection, in order, that don’t contain elements satisfying the given predicate.

func split(separator: Bound, maxSplits: Int, omittingEmptySubsequences: Bool) -> [Slice<ClosedRange<Bound>>]

Returns the longest possible subsequences of the collection, in order, around elements equal to the given element.

Comparing Ranges

static func == (ClosedRange<Bound>, ClosedRange<Bound>) -> Bool

Returns a Boolean value indicating whether two ranges are equal.

static func != (ClosedRange<Bound>, ClosedRange<Bound>) -> Bool

Returns a Boolean value indicating whether two values are not equal.

func overlaps(Range<Bound>) -> Bool

Returns a Boolean value indicating whether this range and the given range contain an element in common.

func overlaps(ClosedRange<Bound>) -> Bool

Returns a Boolean value indicating whether this range and the given range contain an element in common.

Comparing Ranges as Collections

func elementsEqual<OtherSequence>(OtherSequence) -> Bool

Returns a Boolean value indicating whether this sequence and another sequence contain the same elements in the same order.

func elementsEqual<OtherSequence>(OtherSequence, by: (Bound, OtherSequence.Element) -> Bool) -> Bool

Returns a Boolean value indicating whether this sequence and another sequence contain equivalent elements in the same order, using the given predicate as the equivalence test.

func lexicographicallyPrecedes<OtherSequence>(OtherSequence) -> Bool

Returns a Boolean value indicating whether the sequence precedes another sequence in a lexicographical (dictionary) ordering, using the less-than operator (<) to compare elements.

func lexicographicallyPrecedes<OtherSequence>(OtherSequence, by: (Bound, Bound) -> Bool) -> Bool

Returns a Boolean value indicating whether the sequence precedes another sequence in a lexicographical (dictionary) ordering, using the given predicate to compare elements.

func starts<PossiblePrefix>(with: PossiblePrefix) -> Bool

Returns a Boolean value indicating whether the initial elements of the sequence are the same as the elements in another sequence.

func starts<PossiblePrefix>(with: PossiblePrefix, by: (Bound, PossiblePrefix.Element) -> Bool) -> Bool

Returns a Boolean value indicating whether the initial elements of the sequence are equivalent to the elements in another sequence, using the given predicate as the equivalence test.

Manipulating Indices

var startIndex: ClosedRange<Bound>.Index

The position of the first element in the range.

var endIndex: ClosedRange<Bound>.Index

The range’s “past the end” position—that is, the position one greater than the last valid subscript argument.

var indices: DefaultIndices<ClosedRange<Bound>>

The indices that are valid for subscripting the collection, in ascending order.

func index(after: ClosedRange<Bound>.Index) -> ClosedRange<Bound>.Index

Returns the position immediately after the given index.

func formIndex(after: inout ClosedRange<Bound>.Index)

Replaces the given index with its successor.

func index(before: ClosedRange<Bound>.Index) -> ClosedRange<Bound>.Index

Returns the position immediately before the given index.

func formIndex(before: inout ClosedRange<Bound>.Index)

Replaces the given index with its predecessor.

func index(ClosedRange<Bound>.Index, offsetBy: Int) -> ClosedRange<Bound>.Index

Returns an index that is the specified distance from the given index.

func formIndex(inout ClosedRange<Bound>.Index, offsetBy: Int)

Offsets the given index by the specified distance.

func index(ClosedRange<Bound>.Index, offsetBy: Int, limitedBy: ClosedRange<Bound>.Index) -> ClosedRange<Bound>.Index?

Returns an index that is the specified distance from the given index, unless that distance is beyond a given limiting index.

func formIndex(inout ClosedRange<Bound>.Index, offsetBy: Int, limitedBy: ClosedRange<Bound>.Index) -> Bool

Offsets the given index by the specified distance, or so that it equals the given limiting index.

func distance(from: ClosedRange<Bound>.Index, to: ClosedRange<Bound>.Index) -> Int

Returns the distance between two indices.

func hash(into: inout Hasher)

Hashes the essential components of this value by feeding them into the given hasher.

Describing a Range

var description: String

A textual representation of the range.

var debugDescription: String

A textual representation of the range, suitable for debugging.

var customMirror: Mirror

The custom mirror for this instance.

Encoding and Decoding a Range

func encode(to: Encoder)

Encodes this value into the given encoder.

init(from: Decoder)

Creates a new instance by decoding from the given decoder.

Infrequently Used Functionality

func withContiguousStorageIfAvailable<R>((UnsafeBufferPointer<Bound>) -> R) -> R?

Call body(p), where p is a pointer to the collection’s contiguous storage. If no such storage exists, it is first created. If the collection does not support an internal representation in a form of contiguous storage, body is not called and nil is returned.

func index(of: Bound) -> ClosedRange<Bound>.Index?

Returns the first index where the specified value appears in the collection.

Deprecated
init(uncheckedBounds: (lower: Bound, upper: Bound))

Creates an instance with the given bounds.

Supporting Types

enum ClosedRange.Index

A type that represents a position in the collection.

typealias ClosedRange.Element

A type representing the sequence’s elements.

typealias ClosedRange.Iterator

A type that provides the sequence’s iteration interface and encapsulates its iteration state.

typealias ClosedRange.SubSequence

A sequence that represents a contiguous subrange of the collection’s elements.

Type Aliases

typealias ClosedRange.Indices

A type that represents the indices that are valid for subscripting the collection, in ascending order.

Instance Properties

var hashValue: Int

The hash value.

Instance Methods

func difference<C>(from: C) -> CollectionDifference<Bound>

Returns the difference needed to produce this collection’s ordered elements from the given collection.

func difference<C>(from: C, by: (C.Element, Bound) -> Bool) -> CollectionDifference<Bound>

Returns the difference needed to produce this collection’s ordered elements from the given collection, using the given predicate as an equivalence test.

func index(where: (Bound) -> Bool) -> ClosedRange<Bound>.Index?

Returns the first index in which an element of the collection satisfies the given predicate.

Deprecated

Relationships

Conforms To

See Also

Ranges

static func ..< (Self, Self) -> Range<Self>

Returns a half-open range that contains its lower bound but not its upper bound.

struct Range

A half-open interval from a lower bound up to, but not including, an upper bound.

static func ... (Self, Self) -> ClosedRange<Self>

Returns a closed range that contains both of its bounds.

Beta Software

This documentation contains preliminary information about an API or technology in development. This information is subject to change, and software implemented according to this documentation should be tested with final operating system software.

Learn more about using Apple's beta software