Update Sharepoint List Item

Question

I got following error...

System.NullReferenceException: Object reference not set to an instance of an object. at Microsoft.SharePoint.SPListItem.get

Answer 1

Ruben's answer was correct but was getting few errors (may be its was only for me) therefore i tweaked little bit and then it was working fine. Below is the code which i used if anyone needs it

 SPList list = web.Lists["ListName"];
                    //SPListItem item = list.Items.Add();
                    //item["PercentComplete"] = .45; 
                    // 45%//item.Update();
                   SPQuery oQuery = new SPQuery();

                        oQuery.Query = @"               
                                                       
                                                           
                                        Design              
                                                
                                  ";
                        SPListItemCollection collListItems = list.GetItems(oQuery);
                        foreach (SPListItem item in collListItems)
                    {    item["PercentComplete"] = .55;   
                        item.Update();}