static void Main() { GSM nokia = new GSM(null, null); nokia.Battery = new Battery("batt87", 35.5, 3); nokia.gsmBattery = new Battery("batt87", 35.5, 3); nokia.iPhone4s = new GSM("iphone", "apple"); nokia.PhoneManufacturer = "Nokia Corp."; nokia.PhoneModel = "N70"; nokia.PhoneOwner = "bai ganio"; nokia.PhonePrice = 1.01m; nokia.Call.CallDuration = 410; nokia.Call.DialedPhoneNumber = 0888123456; GSM.callHistory.Add(nokia.Call); //leave no null characteristics - fill all battery, owner etc. GSM htc = new GSM(null, null); htc.Battery = new Battery("batt87", 30.5, 3.2); htc.gsmBattery = new Battery("batt87", 35.1, 0.3); htc.iPhone4s = new GSM("iphone", "apple"); htc.PhoneManufacturer = "HTC Corp."; htc.PhoneModel = "One"; htc.PhoneOwner = "bash ganio"; htc.PhonePrice = 1.06m; htc.Call.CallDuration = 110; htc.Call.DialedPhoneNumber = 0877123456; GSM.callHistory.Add(htc.Call); GSM sony = new GSM(null, null); sony.Battery = new Battery("batt87", 25.5, 1.3); sony.gsmBattery = new Battery("batt87", 35.5, 3); sony.iPhone4s = new GSM("iphone", "apple"); sony.PhoneManufacturer = "Sony Corp."; sony.PhoneModel = "Something"; sony.PhoneOwner = "ganio"; sony.PhonePrice = 1.08m; sony.Call.CallDuration = 210; sony.Call.DialedPhoneNumber = 0899123456; GSM.callHistory.Add(sony.Call); GSM samsung = new GSM(null, null); samsung.Battery = new Battery("batt817", 15.5, 4.3); samsung.gsmBattery = new Battery("batt817", 35.5, 3); samsung.iPhone4s = new GSM("iphone", "apple"); samsung.PhoneManufacturer = "samsung Corp."; samsung.PhoneModel = "s520"; samsung.PhoneOwner = "one more ganio"; samsung.PhonePrice = 111.00m; samsung.Call.CallDuration = 262; samsung.Call.DialedPhoneNumber = 0882111111; //GSM.callHistory.Add(samsung.Call); GSM.AddCallsToHistory(samsung.Call); foreach (var call in GSM.CallHistory) { Console.WriteLine("Log Call duration: {0}", call.CallDuration); Console.WriteLine(); } GSM.CalculateTotalCallsCost(GSM.callHistory, 0.27m); //pass current call log and call price pre minute in decimal }