Question

Im trying to get the sum of a list from a web service.

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

        return sum; // error under sum on this line

}

But I get the error cannot convert int to string, this should work?

Client Code:

    public partial class Form1 : Form
    {
        List<int> listInt = new List<int>();

        public Form1()
        {
            InitializeComponent();
        }
        private void Form1_Load(object sender, EventArgs e)
        {

        }
        private void listBox1_SelectedIndexChanged(object sender, EventArgs e)
        {

        }

        private void button1_Click(object sender, EventArgs e)
        {
            listInt.Add(Convert.ToInt32(textBox1.Text));
            textBox1.Clear();
            listBox1.Items.Clear();
            for (int i = 0; i < listInt.Count; i++)
            {
                listBox1.Items.Add(listInt[i]);
            }
        }

        private void button2_Click(object sender, EventArgs e)
        {
            CalculateSumOfList.ServiceReference1.Service1SoapClient client = new CalculateSumOfList.ServiceReference1.Service1SoapClient();
            CalculateSumOfList.ServiceReference1.ArrayOfInt arrayOfInt = new CalculateSumOfList.ServiceReference1.ArrayOfInt();
            arrayOfInt.AddRange(listInt);
            int result = client.CalculateSum(arrayOfInt); //here
            label1.Text = Convert.ToString(result);


        }



    }
}

I get errors with client.CalculateSum(arrayOfInt);

Answer 1

You can use either

 return sum.ToString();

or

return "" + sum;

But do consider first: Should a function that sums int values really return a string? It seems to make much more sense as an int function:

public int CalculateSum(List<int> listInt)
{
    int sum = listInt.Sum();
    return sum;  // now matches the return-type of the method 
}