Instance MethodSwift

    starts(with:)

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

    • Available when Self.Element conforms to Equatable

    func starts<PossiblePrefix>(with possiblePrefix: PossiblePrefix) -> Bool where PossiblePrefix : Sequence, Self.Element == PossiblePrefix.Element

    Parameters

    possiblePrefix

    A sequence to compare to this sequence.

    Returns

    true if the initial elements of the sequence are the same as the elements of possiblePrefix; otherwise, false. If possiblePrefix has no elements, the return value is true.

    Overview

    This example tests whether one countable range begins with the elements of another countable range.

    let a = 1...3
    let b = 1...10
    
    print(b.starts(with: a))
    // Prints "true"

    Passing a sequence with no elements or an empty collection as possiblePrefix always results in true.

    print(b.starts(with: []))
    // Prints "true"