Search Techniques: Linear & Binary

Searching is needed when we have a large array of some data or objects & need to find the position of a particular element. We may also need to check if an element exists in a list or not. While there are built in functions that offer these capabilities, they only work with predefined datatypes. Therefore there may the need for a custom function that searches elements & finds the position of elements. Below you will find two search techniques viz. Linear Search & Binary Search implemented in C#. The code is simple & easy to understand & can be modified as per need.


Linear Search Technique in C Sharp


using System;
using System.Text;
using System.Threading.Tasks;

namespace Linear_Search
{
    class Program
    {
        static void Main(string[] args)
        {
            Int16[] array = new Int16[100];
            Int16 search, c, number;

            Console.WriteLine("Enter the number of elements in array\n");
            number = Convert.ToInt16(Console.ReadLine());

            Console.WriteLine("Enter " + number.ToString() + " numbers\n");

            for (c = 0; c < number; c++)
            {
                array[c] = new Int16();
                array[c] = Convert.ToInt16(Console.ReadLine());
            }

            Console.WriteLine("Enter the number to search\n");
            search = Convert.ToInt16(Console.ReadLine());

            for (c = 0; c < number; c++)
            {
                if (array[c] == search)     /* if required element found */
                {
                    Console.WriteLine("" + search.ToString() + " is present at location " + (c + 1).ToString() +
                    ".\n");
                    break;
                }
            }
            if (c == number)
                Console.WriteLine(search.ToString() + " is not present in array.\n");

            Console.ReadLine();
        }
    }
}

Binary Search Technique in C Sharp

using System;
using System.Text;
using System.Threading.Tasks;

namespace Binary_Search
{
    class Program
    {
        static void Main(string[] args)
        {
            int c, first, last, middle, n, search;
            Int16[] array = new Int16[100];

            Console.WriteLine("Enter number of elements\n");
            n = Convert.ToInt16(Console.ReadLine());

            Console.WriteLine("Enter " + n.ToString() + " integers\n");

            for (c = 0; c < n; c++)
            {
                array[c] = new Int16();
                array[c] = Convert.ToInt16(Console.ReadLine());
            }

            Console.WriteLine("Enter value to find\n");
            search = Convert.ToInt16(Console.ReadLine());

            first = 0;
            last = n - 1;
            middle = (first + last) / 2;

            while (first <= last)
            {
                if (array[middle] < search)
                    first = middle + 1;
                else if (array[middle] == search)
                {
                    Console.WriteLine(search + " found at location " + (middle + 1));
                    break;
                }
                else
                    last = middle - 1;

                middle = (first + last) / 2;
            }
            if (first > last)
                Console.WriteLine("Not found! " + search + " is not present in the list.");

            Console.ReadKey();
        }
    }
}
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