- New
- Display
- Exit
- code must be unique, don't accept dublicated code
- salary must be more than 5K
- bonus must be positive value
- reduction must be less than the half of employee salary
- can't display emplyee till user add at least one employee
- when user display last employee and press next will display first employee info
- when user display first employee and press prev will display last employee info
- when user go back to home, when he return to display, will display last employee before he get out from display page
