Question

Hi with this code I get: cannot implicity convert type string to int.

        CalculateSumOfList.ServiceReference1.Service1SoapClient client = new CalculateSumOfList.ServiceReference1.Service1SoapClient();
        CalculateSumOfList.ServiceReference1.ArrayOfInt arrayOfInt = new CalculateSumOfList.ServiceReference1.ArrayOfInt();
        arrayOfInt.AddRange(listInt);
        int result = client.CalculateSum(arrayOfInt); //error here!
        label1.Text = Convert.ToString(result);

The webmethod I am calling is here:

namespace CalculateWebServiceSum
{
    /// <summary>
    /// Summary description for Service1
    /// </summary>
    [WebService(Namespace = "http://tempuri.org/")]
    [WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
    [System.ComponentModel.ToolboxItem(false)]
    // To allow this Web Service to be called from script, using ASP.NET AJAX, uncomment the following line. 
    // [System.Web.Script.Services.ScriptService]
    public class Service1 : System.Web.Services.WebService
    {

        [WebMethod]
        public string CalculateSum(List<int> listInt)
        {
            int[] sum = listInt.ToArray();

            return sum.ToString();

        }
    }
}

Answer 1

The error message is pretty clear. Your method, CalculateSum() returns a string. On the line that the error occurs, you’re attempting to use the string result to set the value of an int:

int result = client.CalculateSum(arrayOfInt);
^ type int   ^ returns string

Option 1

I suggest changing your CalculateSum() to this:

public int CalculateSum(List<int> listInt)
{
    return listInt.Sum();
}

Note: I’m not sure why you’re passing a List<int> to a web service to be summed. If you have List<int>, simply call List<int>.Sum(), no WS needed.

Option 2

Since you’re calling .ToString() on the int after retrieving it, why not just retrieve it as a string?

string result = client.CalculateSum(arrayOfInt);

public string CalculateSum(List<int> listInt)
{
    return listInt.Sum().ToString();
}