---
title: "starts(with:)"
framework: swift
role: symbol
role_heading: Instance Method
path: "swift/rangeset/ranges-swift.struct/starts(with:)"
---

# starts(with:)

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

## Declaration

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

## Parameters

- `possiblePrefix`: A sequence to compare to this sequence.

## Return Value

Return Value 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.

## Discussion

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 possiblePrefix always results in true. print(b.starts(with: [])) // Prints "true" note: O(m), where m is the lesser of the length of the sequence and the length of possiblePrefix.