passing null for an integer argument

Question

Hi I have developed a web service in c# which takes a parameter as integer type but when i call it without passing any value it gives an error which is natural because it cannot convert null into int32 type. Is there any way i can call this webservice an return a personal error message to the client if he calls the service without passing any value as argument. I tried to change the int type to int? in the function definition but still i am having the problem  is there any other way? Hope to get a reply soon. Thanks Jain

Kirtan Patel · Answer

Friend you can take Object Array instead of int[] as Parameters Where you can pass any-datatype of variable as below one public int sqr(params object[] theObjects) { } now you can use method to pass anytpe of variables ;) sqr(hello123anything); as Object is Convertible to any datatype :) you can convert Object to Int32 By Convert.ToInt32(objectvar); for converting object to String objvar.ToString();

Manish Jain · Answer

Hi I thought of something similar changing int to string in my function definition and checking if its null i return error message if it is not null i change it to integer n use it. Thanks Jain

Manish Jain · Answer

Hi Kirtan yeah i agree its a good way to escape overloading but it is not going to work in my case. My origional method is public DataSet getdataset(string userName string passWord int Id) { } If i call getdataset(usernamepassword) it returns an exception cannot convert string to int32 type.... What i want is something like this inside my webmethod if ( id is not passed ) { DataSet dsErr = new DataSet(); DataTable errTable = dsErr.Tables.Add(Error); errTable.Columns.Add(ID typeof(int)); errTable.Columns.Add(Error typeof(string)); errTable.Rows.Add(1 my personalised error message); errTable.AcceptChanges(); return dsErr; } thanks a lot Manish

Kirtan Patel · Answer

Friend I have came with new Optional Solution if you dont want to create too much methods . here check the below example i have made for you that method can take as much parameters as you want to pass :) first check if user dont pass the parameter then lenght of array will be 0 so return the error :) in this way single method can handle many number of parameters :) from 0 to N... :) public int sqr( params int [] theObjects) { // Check if User passed value or not if length is 0 //then user have not passed the value // Show the error if length of objects is 0 if (theObjects.Length != 0) { int total = 0; foreach ( int i in theObjects) { total += i; } return total; } else { return 0; } }

Manish Jain · Answer

Hi Kirtan Thanks for the suggestion but is there any other way then overloading? Because if i have like 3 or 4 arguments for my method then i have to overload methods for all the combinations :( Thanks Jain

Kirtan Patel · Answer

Friend Here i m Giving your Problem's Solutions :) if my answer helps you then please check do you like this answer check box :) you can Define Two Methods With SameName one With parameter and One Without parameter ( Method Overloading ) but in WebService there is Some Modification you have to do to Achieve Method Overloading I highligheted what you have to change .to achive method overloading in webservice. so in First method Without Parameter Just return error Messsage to User and In Second method Perform the operation you want to do :) thats it :) .csharpcode .csharpcode pre { font-size: small; color: black; font-family: Consolas Courier New Courier Monospace; background-color: #ffffff; /*white-space: pre;*/ } .csharpcode pre { margin: 0em; } .csharpcode .rem { color: #008000; } .csharpcode .kwrd { color: #0000ff; } .csharpcode .str { color: #006080; } .csharpcode .op { color: #0000c0; } .csharpcode .preproc { color: #cc6633; } .csharpcode .asp { background-color: #ffff00; } .csharpcode .html { color: #800000; } .csharpcode .attr { color: #ff0000; } .csharpcode .alt { background-color: #f4f4f4; width: 100%; margin: 0em; } .csharpcode .lnum { color: #606060; } namespace TestOverloadingWebService { [WebService(Namespace = http://tempuri.org/  Description=  Function overloading in Web Services  )] public class OverloadingInWebService : System.Web.Services.WebService { [WebMethod(MessageName = AddInt  Description = Add two integer Value  EnableSession = true )] public int Add( int a int b) { return (a + b); } [WebMethod(MessageName = AddFloat  Description = Add two Float Value  EnableSession = true )] public float Add( float a float b) { return (a + b); } } }