[Eiffel Tips] Determine whether a given year is a leap year in the Gregorian calendar

[eiffel4all]

Leap year

In this little blog will show you how to resolve the Leap year task of Rosetta Code, here it is the Eiffel solution.

What is a Leap Year?

A leap year (also known as an intercalary year or bissextile year) is a calendar year containing one additional day (or, in the case of lunisolar calendars, a month) added to keep the calendar year synchronized with the astronomical or seasonal year Wikipedia Leap year

Leap Year Program In Eiffel

The code below uses DATE class part of the Eiffel time library and the algorithm from the wiki is_leap_year in the code. Both values are printed in the output.

class
    LEAP_YEAR_EXAMPLE

create
    make

feature -- Initialization

    make
            -- Run example.
        local
            l_date: DATE
            l_dates: ARRAY [INTEGER]
        do
            l_dates :=  {ARRAY[INTEGER]}<<1800,1900,1994,1998,1999,2000,2001,2004,2100,2012,2016,1933>>
            create l_date.make_now
            across l_dates as ic loop
                print ("%NIs the year [" + ic.item.out + "] a leap year? " + l_date.is_leap_year (ic.item).out + " - " +                                             is_leap_year (ic.item).out)
            end
        end

    is_leap_year (a_year: INTEGER): BOOLEAN
            -- Is year `a_year' a leap year?
        do
            if a_year \\ 100 = 0 then
                Result := a_year \\ 400 = 0
            else
                Result := a_year \\ 4  = 0
            end
        end
end

Run the code and you will see the following output

Is the year [1800] a leap year? False - False
Is the year [1900] a leap year? False - False
Is the year [1994] a leap year? False - False
Is the year [1998] a leap year? False - False
Is the year [1999] a leap year? False - False
Is the year [2000] a leap year? True - True
Is the year [2001] a leap year? False - False
Is the year [2004] a leap year? True - True
Is the year [2100] a leap year? False - False
Is the year [2012] a leap year? True - True
Is the year [2016] a leap year? True - True
Is the year [1933] a leap year? False - False

Get the code here

  https://github.com/jvelilla/RosettaCode

You will find more examples in Eiffel based on problem descriptions from Rosetta Code

If you are new to Eiffel check the following links

• Getting Started with Eiffel
• Eiffel Tutorials

On upcoming posts, I will show you how :

• Build a REST API using EiffelWeb.
• How to send emails
• and more ...!

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