Question

The task is to count the number of clicks in a webform.

Here is the code.

public partial class _default : System.Web.UI.Page
    {
        int count = 1;
        private void Page_Load(object sender, System.EventArgs e)
        {
            Button btn = new Button();
            btn.Text = "Click Me";
            btn.Click  += btn_Click;
            Label lbl = new Label();
            form1.Controls.Add(btn);
            form1.Controls.Add(lbl);


        }

        protected void btn_Click(object sender, EventArgs e)
        {
            count++;
            //Label1.Text = count.ToString();

        }
    }

The problem is that lbl is not recognised inside btn_Click() … I can’t figure it out… can anyone suggest?

Answer 1

You need to declare lbl outside the page_load method than it will be available to you in button click like this.

Label lbl ;
int count = 1;

private void Page_Load(object sender, System.EventArgs e)
{
    Button btn = new Button();
    btn.Text = "Click Me";
    btn.Click  += btn_Click;
    lbl = new Label();
    form1.Controls.Add(btn);
    form1.Controls.Add(lbl);
}

protected void btn_Click(object sender, EventArgs e)
{
    count++;
    if(lbl !=null)
      lbl.Text = count.ToString();            
}

Because if you create label in the page_load scope of the variable is limited to that method only. So either you declare the label outside the method like as I did or you can give id to label and than search it using FindControl method.