URL encoding converts special characters into numeric sequences so you can include them safely in a URL. The following code creates extension methods for the string class that lets you convert spaces into the string " " and that URL encode and decode strings.

static class StringExtensions
{
    // Extension to replace spaces with  
    public static string SpaceToNbsp(this string s)
    {
        return s.Replace(" ", " ");
    }

    // Url encode an ASCII string.
    public static string UrlEncode(this string s)
    {
        return HttpUtility.UrlEncode(s);
    }

    // Url decode an ASCII string.
    public static string UrlDecode(this string s)
    {
        return HttpUtility.UrlDecode(s);
    }
}

The SpaceToNbsp method simply replaces spaces with the string " ". The UrlEncode and UrlDecode methods use the HttpUtility class's UrlEncode and UrlDecode methods.