How to check whether string contains substring or not in C#?

Consider the program:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication1
{
	class Program
	{
		static void Main()
		{
			string str = "Hello How are you? ";

			if (str.Contains("How") == true)
			{
				Console.WriteLine("Given string contains with in string");
			}
			else
			{
				Console.WriteLine("Given string does not contain with in string");
			}


			if (str.Contains("Who") == true)
			{
				Console.WriteLine("Given string contains with in string");
			}
			else
			{
				Console.WriteLine("Given string does not contain with in string");
			}
		}
	}
}

Output

Given string contains with in string
Given string does not contain with in string 

For first case: We are checking string (substring) "How" in the string str, the condition will be true because string str contains "How" but in other (second) case we are cheking "Who" which is not exists in string str i.e. string str does not contain the substring “Who”. Thus, condition will be false.