Linear Search algorithm

    #include <stdio.h>
    /*
     * Part of Cosmos by OpenGenus Foundation
     * Input: an integer array with size in index 0, the element to be searched
     * Output: if found, returns the index of the element else -1
    */
    int search(int arr[], int size, int x)
    {
        int i=0;
        for (i=0; i<size; i++)
            if (arr[i] == x)
                return i;
        return -1;
    }    
    int main() 
    {
        int arr[] = {2,3,1,5}; // Index 0 stores the size of the array (initially 0)
        int size = sizeof(arr)/sizeof(arr[0]);
        int find = 1;
        printf("Position of %d is %d\n", find, search(arr,size,find));
        return 0;
    }

  /*
     * Part of Cosmos by OpenGenus Foundation
     * Author: Visakh S
     * Github: visakhsuku
     * Input: The number of elements in an array, The element to be searched, An integer array.
     * Output: if found returns "found" else "not found", using the sentinel linear search algorithm.
    */
    #include <iostream>
    #include <vector>
    using namespace std;
    void sentinelLinearSearch(std::vector<int> v,int n,int x)
    {
        int last,i=0;
        last=v[n-1];
        v[n-1]=x;
        while(v[i]!=x)
            i++;
        if(i<n-1||last==x)
            cout<<"found";
        else
            cout<<"not found";
    }
    int main()
    {
        ios_base::sync_with_stdio(false);cin.tie(NULL);
        int n,x,input;
        std::vector<int> v;
        cin>>n>>x;
        for (int i = 0; i < n; ++i)
        {
            cin>>input;
            v.push_back(input);
        }
        sentinelLinearSearch(v,n,x);
        return 0;
    }

// Part of Cosmos by OpenGenus Foundation
import java.util.Scanner;
/**
 * The {@code LinearSearch} class is the simplest of the searching
 * algorithm. The goal of the algorithm is to check the existence of an
 * element in the given array.
 * How it works
 * {@code LinearSearch} goes through each element of the given array until
 * either the element to be searched is found or we have reached the end
 * of the array.
 * Complexity
 * Time Complexity -> O(n)
 * Space Complexity -> O(1) *
 * @author Cosmos by OpenGenus Foundation
 */
class LinearSearch {    
    /*
     * Searches for key in the given array. Returns the index within this
     * array that is the element searched for.
     * @param   arr
     *          Array that is the source of the search.
     * @param   key
     *          The number to be searched for in the array.
     * @return  the index of the element, else -1.
     */  
    static int linearSearch(int arr[], int key) {
        for (int i = 0; i < arr.length; i++) {
            if (arr[i] == key)
                return i;
        }
        return -1;
    }
    /*
     * A recursive implementation of {@link #linearSearch()}
     * @param   arr
     *          Array that is the source of the search.
     * @param   key
     *          The number to be searched for in the array.
     * @return A recursive call to {@link #recursiveLinearSearch()}
     */
    static int recursiveLinearSearch(int arr[], int key) {
        return recursiveLinearSearch(arr, key, 0);
    }
    private static int recursiveLinearSearch(int arr[], int key, int index) {
        // Key not found at all.
        if (index == arr.length)
            return -1;        
        // Key found at current index.
        if (key == arr[index])
            return index;        
        // Else, keep moving through indices
        return recursiveLinearSearch(arr, key, index + 1);
    }    
    public static void main(String args[]) {
        // Object of scanner class to take input.
        Scanner sc = new Scanner(System.in);
        System.out.println("Enter the size of the array to be searched");
        int size = sc.nextInt();
        int arr[] = new int[size];        
        // Loop to take input.
        for(int i = 0; i < size; i++) {
            System.out.println("Enter the element number " + (i + 1) + " of the array");
            arr[i] = sc.nextInt();
        }        
        System.out.println("Enter the number you want to find");
        int key = sc.nextInt();        
        System.out.println("Position of " + key + " is " + linearSearch(arr, key));
        System.out.println("Position of " + key + " is " + recursiveLinearSearch(arr, key));
    }
}

  // Part of Cosmos by OpenGenus
    public class LinearSearch
    {
        public static void Main(string[] args)
        {
            int[] items = new int[] { 10, 12, 52, 634, 24, 743, 234, 7, 25, 742, 76, 25};
        int itemToFind = 634;
        int itemIndex = linearSearch(items, itemToFind);
        if(itemIndex != -1)
            System.Console.WriteLine(itemToFind + " found at " + itemIndex);
        else
            System.Console.WriteLine(itemToFind + " not found!");
    }

    public static int linearSearch(int[] items, int itemToFind)
    {
        for(int i = 0; i < items.Length; i++)
        {
            if(items[i] == itemToFind)
            {
                return i;
            }
        }
        return -1;
    }
}

  ; generally in list processing languages we
    ; we don't work with indices but just in case
    ; you wanted to find position of element from list head
    (defn linear-search-list
          "Returns the position of the list element from head"
          ([tlist elem]                                         ;tlist is a linked list
            (linear-search tlist elem 0))
          ([[x remm] elem idx]
            (if (= x elem)
              idx
              (recur remm elem (inc idx)))))                    ;recursive call with remaining list & args
(defn linear-search-in-vec
      "Function takes persistent vector and searches for elem"
      ([tvec elem]
        (linear-search-in-vec tvec elem idx))
      ([tvec elem idx]
        (if (= elem (get tvec idx))
          idx
          (recur tvec elem (inc idx)))))

;Example usage
(linear-search (list 1 2 3 4 5) 4)
(linear-search-in-vec (vector 1 2 3 4 5 6) 4)

  package main
    import (
        "fmt"
    )
func main() {
    arr := []int{1, 3, 45, 56, 8, 21, 7, 69, 12}
    find := 56
    index := search(arr, find)
    if index != -1 {
        fmt.Printf("%d found at index %d", find, index)
    } else {
        fmt.Printf("%d not found!", find)
    }

}

func search(arr []int, x int) int {
    for i, n := range arr {
        if n == x {
            return i
        }
    }
    return -1
}

    linearsearch :: (Eq a) => [a] -> a -> Maybe Int
    linearsearch [] _ = Nothing
    linearsearch (x:xs) y = if x == y then Just 0 else (1 +)  linearsearch xs y
  

  /*
     * Part of Cosmos by OpenGenus Foundation
     * Input    :   An integer array and the element to be searched
     * Output   :   If found returns the index of element or else -1
     * Example  :
     *              var index = linearSearch([1, 2, 3, 4, 7, 8], 8);
     * 
    */
    function linearSearch(arr, element) {
        for (var i = 0; i < arr.length; i++) {
            if (arr[i] === element) {
                return i;
            }
        }
        return -1;
    }
  

  // Part of Cosmos by OpenGenus Foundation
fun <T> linearSearch(array: Array<T>, key: T): Int? {
    for (i in 0 until array.size) {
        if (array[i] == key) {
            return i
        }
    }
    return null
}

fun main(args: Array<String>) {
    val sample: Array<Int> = arrayOf(13, 17, 19, 23, 29, 31, 37, 41, 43)
    val key = 23

    val result = linearSearch(sample, key)

    println(when (result) {
        null -> "$key is not in sample"
        else -> "Position of $key is $result"
    })
}

  (* Part of Cosmos by OpenGenus Foundation *)
let rec linear_search x = function
  | [] -> -1
  | hd :: tl when hd == x -> 0
  | hd :: tl -> 1 + (linear_search x tl);;

  proc linear_search[T](collection: seq[T], item: T): T =
    for i in 0..(collection.len() - 1):
        if collection[i] == item:
            return i
    return -1
let s = @[42, 393, 273, 1239, 32]
echo linear_search(s, 273) # prints "2"
echo linear_search(s, 32)  # prints "4"
echo linear_search(s, 1)   # prints "-1"

  echo sprintf("Position of %d is %d\n", $search = 33, linearSearch($array = [7, 11, 13, 33, 66], $search));

    '''
    Part of Cosmos by OpenGenus Foundation
    '''
    def linear_search(arr, x):
        for i in range(len(arr)):
            if arr[i] == x:
                return i
        return -1
    arr = []
    while True:
        inp = raw_input("Enter a number (non number to stop):")
        if not inp.isdigit():
            break
        arr.append(int(inp))
find = int(raw_input("Enter the number you want to find: "))
print "Position of " + str(find) + " is " + str(linear_search(arr, find))

  # Part of Cosmos by OpenGenus Foundation
items = [5, 10, 34, 18, 6, 7, 45, 67]
target = 7

#Returns a boolean that indicates whether the target item is contained within
#the given list.
def linear_search(list, target)
  #Iterate over each item in the list
  list.each do |item|
    return true if item == target
  end

  false
end

found = linear_search(items, target)

if found
  puts "Found '#{target}'!"
else
  puts "'#{target}' was not found."
end

  fn search(vec: &[i32], n: i32) -> i32 {
        for i in 0..vec.len() {
            if vec[i] == n {
                return i as i32; // Element found return index
            }
        }
        return -1; // If element not found return -1
    }
fn main() {
    let arr = vec![1, 3, 45, 56, 8, 21, 7, 69, 12];
    let num = 56;
    let index =  search(&arr, num);
    if index != -1 {
        println!("Found {}, at index {}", num, index);
    }else {
        println!("{} not found!", num)
    }
}

      /* Part of Cosmos by OpenGenus Foundation */
object LinearSearch extends App {

  def linearSearch[A: Equiv](list: List[A], element: A): Option[Int] = {
    list match {
      case Nil => None
      case head :: tail => if (head == element) Some(0) else (linearSearch(tail, element).map(_ + 1))
    }
  }

  val list = (0 to 1000) map (_ => scala.util.Random.nextInt(1000))
  val element = scala.util.Random.nextInt(1000)
  val output = linearSearch(list.toList, element)
  Console.println(s"Index: $output")

}

    //
    //  linear_search.swift
    //  test 
    //  Created by Kajornsak Peerapathananont on 10/14/2017 BE.
    //  Copyright © 2560 Kajornsak Peerapathananont. All rights reserved.
    //  Part of Cosmos by OpenGenus Foundation
import Foundation

/*
 Input : array of item and the element that want to be search
 Output : index of element (if found) or else -1
 */
func linear_search<T : Equatable>(array : [T], element : T) -> Int{
    for (index, item) in array.enumerated() {
        if(item == element){
            return index
        }
    }
    return -1
}