Eval in asp.net

 public void item_bound(object sender,DataGridItemEventArgs e)
        {
            try
            {
                if((e.Item.ItemType  == ListItemType.Item) || (e.Item.ItemType  == ListItemType.AlternatingItem))`enter code here`
                {
                    string  Status  =(string)DataBinder.**Eval**(e.Item.DataItem,"customer_status");
                    Image Image = new Image();
                    Image = (Image)e.Item.Cells[1].FindControl("imgbtnstatus");
                    //Image.Command +=new CommandEventHandler(Image_Command);
                    //Image.Attributes.Add("SEmpId  ", SEmpId );
                    if (Status == "Active")
                        Image.ImageUrl = "~/images/activeuser.png";
                    else
                        Image.ImageUrl = "~/images/inactiveuser.png";
                }
            }
            catch(Exce开发者_运维知识库ption ex){Response.Write(ex.ToString());
            }
        }

here is the code for runtime binding the active and inactive image for the users in datagrid...

i want to know what is the use of Eval in above code...

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Eval takes and evaluates the "customer_status" value from the current item in the data source.

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I agree with McKay's answer; I just thought I'd expand a bit on this:

The DataBinder object also as a GetIndexedPropertyValue function that allows you to retrieve things like elements of an array or a dictionary.

For instance, you could do DataBinder.GetIndexedPropertyValue(e.Item.DataItem, "[0]") to get the first element of an array, or you could do DataBinder.GetIndexedPropertyValue(e.Item.DataItem, "[name]") to get a value from a dictionary using the "name" key.

Though there might be a reason for doing this in the code-behind, much of the code from the question could be done in the ASP.Net markup instead:

<asp:Image ID="imgbtnstatus" runat="server" ImageUrl='<%# ((string)DataBinder.Eval(Container.DataItem,"customer_status") == "Active") ? "~/images/activeuser.png" : "~/images/inactiveuser.png" %>' />

Also, since .Net 2.0 an Eval function has been available that replaces DataBinder.Eval(Container.DataItem, ...). The ASP markup in my example could be written as follows:

<asp:Image ID="imgbtnstatus" runat="server" ImageUrl='<%# ((string)Eval("customer_status") == "Active") ? "~/images/activeuser.png" : "~/images/inactiveuser.png" %>' />

The Eval function can also be used to retrieve values similar to the DataBinder.GetIndexedPropertyValue function by passing a string enclosed in square brackets.