Linear Search Algorithm and Implementation in C

Linear_Search ( Array X, Value i)

• Set j to 1
• If j > n, jump to step 7
• If X[j] == i, jump to step 6
• Then, increment j by 1 i.e. j = j+1
• Go back to step 2
• Display the element i which is found at particular index i, then jump to step 8
• Display element not found in the set of input elements.
• Exit/End

procedure LINEAR_SEARCH (array, key)

   for each item in the array
      if match element == key
         return element's index
      end if
   end for

end procedure

• Initially, we need to mention or accept the element to be searched from the user.
• Then, we create a for loop and start searching for the element in a sequential fashion.
• As soon as the compiler encounters a match i.e. array[element] == key value, return the element along with its position in the array.
• If no values are found that match the input, it returns -1.

#include <stdio.h> 

int LINEAR_SEARCH(int inp_arr[], int size, int val) 
{ 
	 
	for (int i = 0; i < size; i++) 
		if (inp_arr[i] == val) 
			return i; 
	return -1; 
} 


int main(void) 
{ 
	int arr[] = { 10, 20, 30, 40, 50, 100, 0 }; 
	int key = 100; 
	int size = 10; 
	int res = LINEAR_SEARCH(arr, size, key); 
	if (res == -1)
	printf("ELEMENT NOT FOUND!!");
    else
    printf("Item is present at index %d", res);
    
	return 0; 
} 

Output:

Item is present at index 5

The best-case complexity is O(1) if the element is found in the first iteration of the loop.

The worst-case time complexity is O(n), if the search element is found at the end of the array, provided the size of the array is n.

Thus, in this article, we have understood and implemented Linear Search Algorithm.