public void ButtonClickAction(object parameter) { String paramString = parameter.ToString(); if (paramString == "backspace") { if (lastParamString == "+" || lastParamString == "-" || lastParamString == "*" || lastParamString == "/" || lastParamString == "=") { calculatorModel.Reset(); InputTextBox = "0"; } if (inputTextBox != "") { InputTextBox = inputTextBox.Remove(inputTextBox.Length - 1); } if (inputTextBox == "") { InputTextBox = "0"; } } else if (paramString == "0" || paramString == "1" || paramString == "2" || paramString == "3" || paramString == "4" || paramString == "5" || paramString == "6" || paramString == "7" || paramString == "8" || paramString == "9" || paramString == ".") { if (lastParamString == "=") { calculatorModel.Reset(); inputTextBox = ""; } AddCharToInput(paramString[0]); } else if (paramString == "clear") { InputTextBox = "0"; calculatorModel.Reset(); } else if (paramString == "+" || paramString == "-" || paramString == "*" || paramString == "/" || paramString == "=") { double inputValue = 0; if (InputTextBox != "") { inputValue = Double.Parse(InputTextBox); } calculatorModel.InputNumber(inputValue); calculatorModel.InputOperator(StringToOperator(paramString)); InputTextBox = calculatorModel.GetCurrentResult().ToString(); if (paramString != "=") { inputTextBox = ""; } } lastParamString = paramString; }