Need help to work on dropdownlist when pagepostback

I have created simple webform with two dropdownlists which get loaded with numbers on page load event. I have add, sub, mul, divide buttons to operate calculation and a label to display result.

When i select two numbers from dropdownlist and hit the buttons, I got 0 as result.

My Code:

protected void Page_Load(object sender, EventArgs e)

{

MyCalculationClient mc = new MyCalculationClient();

DropDownList1.DataSource = mc.DisplayNumbers();

DropDownList1.DataTextField = "Number";

DropDownList1.DataBind();

DropDownList2.DataSource = mc.DisplayNumbers();

DropDownList2.DataTextField = "Number";

DropDownList2.DataBind();

}

protected void Button1_Click(object sender, EventArgs e)

{

int a = Convert.ToInt32(DropDownList1.Text);

int b = Convert.ToInt32(DropDownList2.Text);

MyCalculationClient add = new MyCalculationClient();

Label1.Text = add.Add(a, b).ToString();

}

Hi Gaurav,

In the Page_Load event, place all your code into "If(!isPostback) condition as shown below.

protected void Page_Load(object sender, EventArgs e)

{

If(!isPostback)

{
MyCalculationClient mc = new MyCalculationClient();
DropDownList1.DataSource = mc.DisplayNumbers();
DropDownList1.DataTextField = "Number";
DropDownList1.DataBind();
DropDownList2.DataSource = mc.DisplayNumbers();
DropDownList2.DataTextField = "Number";
DropDownList2.DataBind();
}

}

Basically, the Page_Load events gets executed for every postback to the page. So, even when the Button is clicked, the Page_Load event gets fired even before the Button1_Click event is executed. So, If you select any two numbers in the dropdowns they would be reset to the default (very first number in your dropdowns. I think it is Zero in your case). So, It is always Zero.

Hope It helped and let me know if you still face any problems,

Prawin