using System;

using System.Linq;

using System.Globalization;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("android mobile 32 gb");

         string searchTerm = "android intel i5";

​

            int itemIndex = GetMatchingIndex(searchTerm);

        Console.WriteLine("index : {0}",itemIndex);

    }

     public static int GetMatchingIndex(string searchKey)

        {

            string[] MyValues = new string[] { "windows", "dual sim", "32 gb", "Intel i5" };

            for (int i = 0; i < MyValues.Count() ; i++)

            {

                    if (searchKey.IndexOf(MyValues[i], StringComparison.InvariantCultureIgnoreCase) >= 0)

                    return i;

            }

            return -1;

        }

}