How Can I Check if Eval Is Null And Ignore It RSS

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C#

C#4.0

Good day, I have this Simple Gridview using Eval

<asp:TemplateField HeaderText = "Quantity Delivered" SortExpression="TotalQDelivered">
                <ItemTemplate>

                 <asp:Label ID="lblQuantityDelivered"  runat="server" Text='<%#Eval("TotalQDelivered") %>' />
                        
                </ItemTemplate>
                </asp:TemplateField>

if (e.Row.RowType == DataControlRowType.DataRow)
            {
              
               int TotalQuantity= 0;
                TotalQuantity  += Convert.ToInt32(DataBinder.Eval(e.Row.DataItem, "TotalQDelivered"));
               
            }
 if (e.Row.RowType == DataControlRowType.Footer)
            {
                Label lblamount = (Label)e.Row.FindControl("lblTotal");
 lblamount.text =  TotalQuantity.ToString();

             }

// I get this Error Object cannot be cast from DBNull to other types. 
// I must Say that some of the rows are null in the Gridview, 

//How do i ignore the null values so that the rows with values can be calculated..

thanks for wonderful time..