Linear Search Program in C, C++ - Algorithm , Time Complexity

Write a C, C++ program to implement a linear search algorithm.

Linear Search

Linear search is a simple search algorithm for searching an element in an array. It works by comparing each element of an array. It is the most basic and easiest algorithm in computer science to find an element in a list or an array.

The time complexity of Linear Search is O(n).

For example -

Let's take an array int arr[] = { 2,1,7,5,9}

Suppose we have to search an element 5. Using linear search, We compare 5 with each element of an array. If 5 exists in an array then we return the index.

Program to merge two arrays.

Binary Search Program in C, C++

Linear Search Time Complexity

In worst case, the time complexity of linear search is O(n). Worst case occurs, when search element is found at the end of an array.

In terms of time complexity, Binary Search is better than linear search. 

C, C++ Interview Questions

Time complexity of sorting algorithm

Linear Search Program in C++

#include<iostream>
using namespace std;

int main()
{

   int arr[50], i, size, num, flag = 0; 

   cout << "Enter the size of an array (Max 50)";
   cin >> size;

   cout << "Enter the "<< size <<" values in an array ";

   for(i = 0; i < size; i++)
   {   
      cin >> arr[i];
   }   

   cout << "Enter the value to be search ";
   cin  >> num;
   
   /* Iterate and compare each element of an array 
      to the value to be searched. */

   for(i = 0; i < size; i++)
   {  
     /* If value is found, 
         then set the flag and break. */ 
      if(arr[i] == num)
      {   
         flag = 1;
         break;
      }   
   }   
 
  if(flag == 0)
      cout <<" Element is not found in an array ";

  else
     cout << " Element is found at position " << (i+1);

   return 0;
}  

Linear Search Program in C

#include <stdio.h>

int main(void) {
 
   int arr[50], n, num, i, flag = 0;
 
   /* Take the size of an array */
   printf ("Enter the size of an array (Max 50)\n");
   scanf ("%d", &n);
 
   printf ("Enter elements in an array \n");
 
   for (i = 0; i < n; i++) {
  
       scanf ("%d", &arr[i]);
   }
 
   printf ("Enter the element to be searched for \n");
   scanf ("%d", &num);
 
   for (i =0; i < n; i++) {
  
      if (arr[i] == num) {
   
          flag = 1;
          break;
      }
   }
 
   if (flag) {
  
       printf ("Element is found at position %d ", i+1);
   
    } else {
  
        printf ("Element is not found");
  
    }
   return 0;
}

Output :

Enter the size of an array (Max 50) : 5

Enter elements in an array :  8     9     3      6      5

Enter the element to be searched : 5

Element is found at position 4


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