Swift program to get the first n elements from an array

SwiftServer Side ProgrammingProgramming

An array is an ordered collection which is used to store same type of data. It can be mutable or immutable.

In an array, we can find the first n elements very easily using any of the following method.

Below is a demonstration of the same −

Input

Suppose our given input is −

myArray = [ 34, 35, 56, 66, 99, 22]
Number = 3

Output

The desired output would be −

First 3 elements = [ 34, 35, 56]

Method 1 - Using half opened range operator with one-side ranges

In Swift, we can get the first n elements from the specified array using half opened range operator with one side range that is [..<y] As we know that a range starts from x to y, so this range starts from x but does not contain y. Or we can say that this range include first values but doesn’t contain end value.

Syntax

Following is the syntax −

var res = myArr[..<number]

Algorithm

Following is the algorithm −

  • Step 1− Declare an array with value.

  • Step 2− Getting the first four or n elements from an array using half op ened operator with one side range.

var result = myArray[..<4]
  • Step 3− Print the output.

Example

The following program shows how to get the first n elements from an array.

import Foundation import Glibc var myArray = [23, 87, 97, 37, 29, 383, 32, 2, 1] // Getting the first 4 elements from the array // Using one sided half-open range operator var result = myArray[..<4] print("The array =",myArray) print("The first 4 elements of an array", result)

Output

The array = [23, 87, 97, 37, 29, 383, 32, 2, 1] 
The first 4 elements of an array [23, 87, 97, 37]

Here in the above code, we have an array [ 87, 97, 37, 29, 383, 32, 2, 1]. Now we display the first 4 elements from the array using half open range operator

var result = myArray[..<4]

This operator will r eturn the first four elements from the array that are − [ 23 , 87, 97, 37]

Method 2 - Using prefix() function

Swift provide an in built function named prefix to find the first n elements from the specified array. It takes one argument that is the required number of elements.

Syntax

Following is the syntax −

var res = myArr.prefix(number)

Algorithm

Following is the algorithm −

  • Step 1− Declare an array with value.

  • Step 2− Getting the first two or n elements from an array using prefix().

var result = myArray.prefix(2)
  • Step 3− Print the output.

Example

The following program shows how to get the first n elements from an array.

import Foundation import Glibc var myArray = ["Bus", "Car", "Bike", "Boat", "Bicycle"] // Getting the first 2 elements from the array // Using prefix() function var result = myArray.prefix(2) print("The array =",myArray) print("The first 2 elements of an array:", result)

Output

The array = ["Bus", "Car", "Bike", "Boat", "Bicycle"]
The first 2 elements of an array: ["Bus", "Car"]

Here in th e above code, we have an array ["Bus", "Car", "Bike", "Boat", "Bicycle"] Now we display the first 2 elements from the array using prefix() function

var result = myArray.prefix(2)

This operator will return the first two elements from the array that are: ["Bus","Car"]

raja
Updated on 10-Oct-2022 13:02:56

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