I've never used C# nor have I created Web Services, so I am in the process
of finding tutorials on the web and going through them.  I found this one
over at code project:

http://www.thecodeproject.com/cs/webservices/myservice.asp

I am presented with this method:

   [WebMethod]
   public ClientData[] GetClientData(int Number)
   {
       ClientData [] Clients = null;

       if (Number > 0 && Number <= 10)
       {
           Clients = new ClientData[Number];
           for (int i = 0; i < Number; i++)
           {
               Clients[i].Name = "Client " + i.ToString();
               Clients[i].ID = i;
           }
       }
       return Clients;
   }

Anyhow, on the web page for GetClientData, I decide not to type in a value
for the Number field and I click the 'Invoke' button.  I receive this:

System.ArgumentException: Cannot convert  to System.Int32.
Parameter name: type ---> System.FormatException: Input string was not in a
correct format.
 at System.Number.ParseInt32(String s, NumberStyles style, NumberFormatInfo
info)
 at System.String.System.IConvertible.ToInt32(IFormatProvider provider)
 at System.Convert.ChangeType(Object value, Type conversionType,
IFormatProvider provider)
 at System.Web.Services.Protocols.ScalarFormatter.FromString(String value,
Type type)
 --- End of inner exception stack trace ---
 at System.Web.Services.Protocols.ScalarFormatter.FromString(String value,
Type type)
 at
System.Web.Services.Protocols.ValueCollectionParameterReader.Read(NameValueC
ollection collection)
 at System.Web.Services.Protocols.HtmlFormParameterReader.Read(HttpRequest
request)
 at System.Web.Services.Protocols.HttpServerProtocol.ReadParameters()
 at System.Web.Services.Protocols.WebServiceHandler.Invoke()
 at System.Web.Services.Protocols.WebServiceHandler.CoreProcessRequest()

Question #1:
What can I use to determine if a user has passed a parameter correctly?  Or
even at all?  Is the value null - since I didn't put in a value?  But how wo
uld you compare an int to null!?

Question #2:
Is it possible to have default parameters (so it would default to a certain
value)?

Question #3:
How do I DEBUG a Web Service?  I set a breakpoint so I could try to figure
out what the Number value was - I pressed F5, it launched a browser, I
clicked the Invoke button - it didn't reach my breakpoint.

Yep.  As you can see, I am really brand-y-newbie here.

Thanks!