private bool IsValidData(Calculator calc)
{
return(calc.IsPresent(this.txtOperand1, "Operand 1") &&
calc.IsDecimal(this.txtOperand1, "Operand 1") &&
calc.IsPresent(this.txtOperator, "Operator") &&
calc.IsValidOperator(this.txtOperator) &&
calc.IsPresent(this.txtOperand2, "Operand 2") &&
calc.IsDecimal(this.txtOperand2, "Operand 2"));
}