Calander Month Program.

The problem is to display a calendar month for any
given month between January 1800 and December
2099. The format of the month should be as shown:

Sun Mon Tue Wed Thu Fri Sat
------------1----2----3---4--5-
-6----7----8----9---10--11--12
13--14---15---16---17-18--19
20--21---22---23---24-25--26
27--28---29---30---31

Need an algorithm for computing the first day of a
given month for years 1800 through 2099...

...and an algorithm for appropriately displaying
the calendar month, given the day of the week that
the first day falls on, and the number of days in
the month.

Year and month entered and stored as integer values.
Represented by variables year and month.

         year = 2012    month = 5  

Remaining values will be computed by the program based
on the given year and month, as given below,

leap_year    num_days_in_month    day_of_week  

The variable leap_year holds a Boolean (True/False) value.
Variables num_days_in_month and day_of_week both hold
integer values.

a) determine day of week a given date falls on.
    1. Let *century_digits* be equal to the first two digits of the year.
    2. Let year_digits be equal to the last two digits of the year.
    3. Let __value__ be equal to __year_digits__ + floor(__year_digits__/4)
    
b) determine how many days are in a given month.