isHappy?

gistfile1.txt

Write a function called isHappy that takes a number as a parameter, and determines whether or not that number is "happy," returning true or false.

How to determine if a number is happy:

7 is happy
-> 7x7 = 49
-> 4x4 + 9x9 = 97
-> 9x9 + 7x7 = 81+49 = 130
-> 1x1 + 3x3 + 0x0 = 10
-> 1x1 + 0x0 = 1 => true

An example sad number is 2:
-> 2x2 = 4
-> 4x4 = 16
-> 1x1 + 6x6 = 37
-> 3x3 + 7x7 = 58
-> 5x5 + 8x8 = 89
-> 8x8 + 9x9 = 145
-> 1x1 + 4x4 + 5x5 = 42
-> 4x4 + 2x2 = 20
-> 2x2 + 0x0 = 4 => false

If the algorithm reaches a sum that is 1, the number is happy.
If it finds a sum that it's already found, the number is sad.

public static bool ishappy(int num)
{
List seen = new List();
seen.Add(num);

        List<int> multiples = new List<int>();
        while (true)
        {
            int digits = numdigits(num);

            int moddder = 10;
            for (int i = 1; i <= digits; i++)
            {
                int digit = getdigit(num,i);
                multiples.Add(digit);
            }
            int total = 0;
            foreach (int m in multiples)
            {
                total += (m * m);
            }

            if (seen.Contains(total))
                return false;
            if (total == 1)
                return true;
            seen.Add(total);
            num = total;
            multiples.Clear();
            Console.WriteLine("Just calculated " + total);
        }            
    }

    public static int getdigit(int num,int digit)
    {
        int val;
        int middle = num/(int)(Math.Pow(10,digit-1));
        val = middle % 10;
        return val;
    }
    public static int numdigits(int num)
    {
        int digits = 1;
        if (num < 10)
            return digits;          
        while (num >= 10)
        {
            digits++;
            num /= 10;
        }
        return digits;
    }

    static void Main(string[] args)
    {
        Console.WriteLine("+++++++++++++++++++++++++++++++++++++++");
        Console.WriteLine("+ Welcome to eBay SDK for .Net Sample +");
        Console.WriteLine("+ - ConsoleAddFixedPriceItem          +");
        Console.WriteLine("+++++++++++++++++++++++++++++++++++++++");

        //[Step 1] Initialize eBay ApiContext object
        ApiContext apiContext = GetApiContext();

        Console.WriteLine(ishappy(7));
        Console.WriteLine(ishappy(2));
    }

function isHappy(num) { // num is integer and >= 0.  bool
     var alreadyChecked = {};   
    while(typeof alreadyChecked[num] === "undefined") {
        var numArray = num.toString().split("");
        var sum = 0;
        for(var i = 0; i < numArray.length; i++) {
            sum += numArray[i] * numArray[i];
        }
        if(sum === 1) {
            return true;
        }
        else {
            alreadyChecked[num] = num;
            num = sum;        
        }   
    }
    return false;
}