using System;

using System.Linq;

public class Program

{

    public static void Main()

    {

        var hello = "Hello World";

        //string output = new string(hello.Where(c => !char.IsWhiteSpace(c)).ToArray());

        string output = RemoveWhiteSpace(hello);

        Console.WriteLine(output);

    }

    public static string RemoveWhiteSpace(string input)

    {

        return new string(input.Where(c => !char.IsWhiteSpace(c)).ToArray());

    }

}

​

​

​

​