WebAddress.cs

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

namespace WebAddess.cs
{
    class Program
    {
        static void Main(string[] args)
        {
            string webadress = "";
            int lcv = 1;
            while (lcv < 5)
            {
                Console.Write("Enter a web address: ");
                webadress = Console.ReadLine();
                if(webadress.All(char.IsLetterOrDigit))
                {
                    webadress = webadress.Replace(" ", "");
                    Console.WriteLine("Web address is valid");
                    break;
                }
                else
                {
                    Console.WriteLine("Web address invalid.");
                }
            }
            Console.WriteLine("Your web address is: \n" +
                "www." + webadress + ".com");
            Console.ReadLine();
        }
    }
}