Linear Search

Linear Search

Let’s say we have array[] that consists of n elements.
And now our task is to write a method that will find the element selected by us in this array.

Data:

Let’s say we have an array with this data.
Array[] = {30, 60, 80, 90, 130, 150, 210, 260, 400, 460, 20, 90, 50, 330, 220}

Purpose, Assumptions:

And we are looking for the element = 50,
So the answer should be the index of this element = 12,

And when we look for an element in this array that is not in it, e.g. 100
in response we should get the index of this element = -1
which will mean that such an element is not in the array.

Solution:

A simple approach to doing this is to perform a linear search.
We start with the leftmost element of array[] and take turns comparing the search element to each element in array[].

If the searched element matches an element of the array, the index of that element is returned. If the searched element does not match any of the elements, we return -1,
which tells us that the element we are looking for is not in the array.

Implementation in C# code

public static void Main()
{
   int[] array = { 30, 60, 80, 90, 130, 150, 210, 260, 400, 460, 20, 90, 50, 330, 220 };
   int theElementLookingFor = 50;

   int result = LinearSearch(array, theElementLookingFor);

   if (result == -1)
      Console.WriteLine(@"Element {0} is not in the array", theElementLookingFor);
   else
	Console.WriteLine("Element {0} is present at index  in the array {1}", theElementLookingFor, result);
}

private static int LinearSearch(int[] array, int theElementLookingFor)
{
   for (int i = 0; i < array.Length; i++)
   {
	if (array[i] == theElementLookingFor)
	   return i;
   }
   return -1;
}

Output:

Element 50 is not in the array 12
or
Element 100 is not in the array