C# Extension To Get Subdomain from URL

Recently, I come across a simple problem where we have to extract subdomain from different URL. Then I decided to write simple extensions in “C# Subdomain from URL”, which can be used easily across the system.

Sharing the code:

public enum GetSubDomainEnum
{
    ExcludeWWW,
    IncludeWWW
};

public static class Extentions
{
    public static string GetSubDomain(this Uri uri,
        GetSubDomainEnum getSubDomainOption = GetSubDomainEnum.IncludeWWW)
    {
        var subdomain = new StringBuilder();
        for (var i = 0; i < uri.Host.Split(new char[]{'.'}).Length - 2; i++)
        {
            if(getSubDomainOption == GetSubDomainEnum.ExcludeWWW && uri.Host.Split(new char[]{'.'})[i].ToLowerInvariant() == "www") continue;
            subdomain.Append((i < uri.Host.Split(new char[]{'.'}).Length - 3 && 
                              uri.Host.Split(new char[]{'.'})[i+1].ToLowerInvariant() != "www") ?                     
                                   uri.Host.Split(new char[]{'.'})[i] + "." :
                                   uri.Host.Split(new char[]{'.'})[i]);
        }
        return subdomain.ToString();
    }
}

USAGE:

var subDomain = Request.Url.GetSubDomain(GetSubDomainOption.ExcludeWWW);