The prefix()
method returns the specified number of elements from the starting element.
Example
var numbers = [2, 4, 6, 8, 10, 11, 12, 13]
// return first 5 elements
print(numbers.prefix(5))
// Output: [ 2, 4, 6, 8, 10 ]
prefix() Syntax
The syntax of the array prefix()
method is:
array.prefix(number: Int)
Here, array is an object of the Array
class.
prefix() Parameters
The prefix()
method takes a single parameter:
- number - number of elements to return from array
Note: number
must be greater than or equal to 0.
prefix() Return Value
- returns the specified number of elements from the starting element.
Example 1: Swift Array prefix()
var languages = ["Swift", "C", "Java", "Objective-C", "Kotlin"]
// return first 3 elements
print(languages.prefix(3))
var prime = [9, 12, 52, 43]
// return first 2 elements
print(prime.prefix(2))
Output
["Swift", "C", "Java"] [9, 12]
In the above example,
languages.prefix(3)
returns the first 3 elements of the languages arrayprime.prefix(2)
returns the first 2 elements of the prime array.
Example 2: Return Empty And Original Array using prefix()
var names = ["Greg", "Ludovico", "Ben", "Cartman"]
// return empty array
print(names.prefix(0))
// return original array
print(names.prefix(4))
Output
[] ["Greg", "Ludovico", "Ben", "Cartman"]
Here,
names.prefix(0)
- since we have passed 0, the method returns an empty array.names.prefix(4)
- since the number of elements to return (4) is equal to the number of elements in the array, the method returns the original array.
Note: Even if the number of elements to return is greater than the number of elements in the array, the method returns the original array.