Returns a Boolean value indicating whether the initial elements of the sequence are the same as the elements in another sequence.
SDK
- Xcode 9.0+
Framework
- Swift Standard Library
Declaration
Parameters
possiblePrefixA sequence to compare to this sequence.
Return Value
true if the initial elements of the sequence are the same as the elements of possible; otherwise, false. If possible has no elements, the return value is true.
Discussion
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 possible always results in true.
print(b.starts(with: []))
// Prints "true"
Complexity: O(m), where m is the lesser of the length of the sequence and the length of possible.