How do you write a pascal program using the case statement to display the days of the week?

Answer 1

Normally we would represent the days of the week using a low-level enumeration:

type

DayOfWeek (Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday);

In other words, Sunday is represented by the integer 0, Monday by 1, Tuesday by 2, etc. This provides with a compact method of representing the high-level concept of a day of the week and the symbolic names are sufficiently abstract to make them easy to work with. However, it would be useful to convert these low-level symbolic constants to their higher-level equivalents (the actual strings, 'Sunday', 'Monday', 'Tuesday', etc) which can then be presented to the user. It would also be useful to be able to perform the reverse conversion, from high-level string to low-level enumeration. We achieve this with conversion functions implemented as lookup tables using case statements:

function ToDayOfWeekStr (Dow : DayOfWeek) : string;

begin

case Dow of

Sunday: ToDayOfWeekStr := 'Sunday';

Monday: ToDayOfWeekStr := 'Monday';

Tuesday: ToDayOfWeekStr := 'Tuesday';

Wednesday: ToDayOfWeekStr := 'Wednesday';

Thursday: ToDayOfWeekStr := 'Thursday';

Friday: ToDayOfWeekStr := 'Friday';

Saturday: ToDayOfWeekStr := 'Saturday';

end

end

function ToDayOfWeekEnum (Dow : string) : DayOfWeek;

begin

case Dow of

'Sunday': ToDayOfWeekEnum := Sunday;

'Monday': ToDayOfWeekEnum := Monday;

'Tuesday': ToDayOfWeekEnum := Tuesday;

'Wednesday': ToDayOfWeekEnum := Wednesday;

'Thursday': ToDayOfWeekEnum := Thursday;

'Friday': ToDayOfWeekEnum := Friday;

'Saturday': ToDayOfWeekEnum := Saturday;

else {handle input errors here};

end

end