Assignment 96

import java.util.Scanner;

public class WeekdayCalculator
{
	public static void main( String[] args )
	{
		Scanner keyboard = new Scanner(System.in);

		System.out.println("Welcome to my fantastic birth-o-meter!");
		System.out.println();
		System.out.println("All you have to do is enter your birth date, and it will");
		System.out.println("tell you the day of the week on which you were born.");
		System.out.println();
		System.out.println("Some automatic tests....");
		System.out.println("12 10 2003 => " + weekday(12,10,2003));
		System.out.println(" 2 13 1976 => " + weekday(2,13,1976));
		System.out.println(" 2 13 1977 => " + weekday(2,13,1977));
		System.out.println(" 7  2 1974 => " + weekday(7,2,1974));
		System.out.println(" 1 15 2003 => " + weekday(1,15,2003));
		System.out.println("10 13 2000 => " + weekday(10,13,2000));
		System.out.println();

		System.out.println("Now it's your turn!  What's your birthday?");
		System.out.print("Birth date (mm dd yyyy): ");
		int mm = keyboard.nextInt();
		int dd = keyboard.nextInt();
		int yyyy = keyboard.nextInt();

		System.out.println("You were born on " + weekday(mm,dd,yyyy) + "!");
	}


	public static String weekday( int mm, int dd, int yyyy )
	{
		int yy, total;
		String date = "";

		yy = yyyy - 1900;
        total = yy / 4 + yy + dd + month_offset(mm);
        if (isLeap(yyyy)&&(mm==1||mm==2))
        {
            total = total - 1 ;
        }

		date = weekday_name(total%7) + ", " + month_name(mm) + " " + dd + ", " + yyyy;

		return date;
	}
    
    public static String month_name( int mm )
	{
		String result;
		
        if (mm==1)
            result = "January";
        else if (mm==2)
            result = "February";
		else if (mm==3)
            result = "March";
		else if (mm==4)
            result = "April";
		else if (mm==5)
            result = "May";
		else if (mm==6)
            result = "June";
		else if (mm==7)
            result = "July";
		else if (mm==8)
            result = "August";
		else if (mm==9)
            result = "September";
		else if (mm==10)
            result = "October";
		else if (mm==11)
            result = "November";
		else if (mm==12)
            result = "December";
		else
            result = "error";
            
		return result;
	}
    
	public static int month_offset( int mm )
	{
		int result;
		
        if (mm==1)
            result = 1;
        else if (mm==2)
            result = 4;
		else if (mm==3)
            result = 4;
		else if (mm==4)
            result = 0;
		else if (mm==5)
            result = 2;
		else if (mm==6)
            result = 5;
		else if (mm==7)
            result = 0;
		else if (mm==8)
            result = 3;
		else if (mm==9)
            result = 6;
		else if (mm==10)
            result = 1;
		else if (mm==11)
            result = 4;
		else if (mm==12)
            result = 6;
		else
            result = -1;
            
		return result;
	}
    
    public static String weekday_name( int weekday )
	{
		String result = "";

		if ( weekday == 1 )
		{
			result = "Sunday";
		}
		else if ( weekday == 2 )
		{
			result = "Monday";
		}
		else if ( weekday == 3 )
		{
			result = "Tuesday";
		}
		else if ( weekday == 4 )
		{
			result = "Wednesday";
		}
		else if ( weekday == 5 )
		{
			result = "Thursday";
		}
		else if ( weekday == 6 )
		{
			result = "Friday";
		}
		else if ( weekday == 7 )
		{
			result = "Saturday";
		}
		else if ( weekday == 0 )
		{
			result = "Saturday";
		}
        else
        {
            result = "error";
        }
		
		return result;
	}
		
	public static boolean isLeap( int yyyy )
	{
		boolean result;

		if ( yyyy%400 == 0 )
			result = true;
		else if ( yyyy%100 == 0 )
			result = false;
		else if ( yyyy%4 == 0 )
			result = true;
		else
			result = false;
		
		return result;
	}
}