---
title: "lexicographicallyPrecedes(_:)"
framework: swift
role: symbol
role_heading: Instance Method
path: "swift/lazymapsequence/lexicographicallyprecedes(_:)"
---

# lexicographicallyPrecedes(_:)

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

## Declaration

```swift
func lexicographicallyPrecedes<OtherSequence>(_ other: OtherSequence) -> Bool where OtherSequence : Sequence, Self.Element == OtherSequence.Element
```

## Parameters

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

## Return Value

Return Value true if this sequence precedes other in a dictionary ordering; otherwise, false.

## Discussion

Discussion This example uses the lexicographicallyPrecedes method to test which array of integers comes first in a lexicographical ordering. let a = [1, 2, 2, 2] let b = [1, 2, 3, 4]

print(a.lexicographicallyPrecedes(b)) // Prints "true" print(b.lexicographicallyPrecedes(b)) // Prints "false" note: This method implements the mathematical notion of lexicographical ordering, which has no connection to Unicode.  If you are sorting strings to present to the end user, use String APIs that perform localized comparison. note: O(m), where m is the lesser of the length of the sequence and the length of other.