I just tried to write a function to validate URL address. Well, as usual, I've done some researches on Google and not many efficient and satisfy solutions. However, I've got a solution which is using Regex in C# to validate a URL and it seems a acceptable method to test the URL input.

public static bool IsValidUrl(this string url)
    string strRegex = "^(https?://)"
        + "?(([0-9a-z_!~*'().&=+$%-]+: )?[0-9a-z_!~*'().&=+$%-]+@)?" // user@
        + @"(([0-9]{1,3}\.){3}[0-9]{1,3}" // IP-
        + "|" // allows either IP or domain
        + @"([0-9a-z_!~*'()-]+\.)*" // tertiary domain(s)- www.
        + @"([0-9a-z][0-9a-z-]{0,61})?[0-9a-z]" // second level domain
        + @"(\.[a-z]{2,6})?)" // first level domain- .com or .museum is optional
        + "(:[0-9]{1,5})?" // port number- :80
        + "((/?)|" // a slash isn't required if there is no file name
        + "(/[0-9a-z_!~*'().;?:@&=+$,%#-]+)+/?)$";

    return new Regex(strRegex).IsMatch(url);