AddOne

Problem

Implement C# function int addone(int n) which will return n+1. You can NOT use any of the following arithmetical operations in the fuction body: + - * / ++ -- += -=.

Solution

using NUnit.Framework;

namespace Developer.Test.Net
{
    [TestFixture]
    public class TestModulus
    {
        [Test]
        public void TestAddOne()
        {
            for (int i = -1000; i < 1000; i++)
            {
                Assert.AreEqual(i + 1, AddOne(i));
            }

            int j = int.MaxValue;

            Assert.AreEqual(j + 1, AddOne(j));

            j = int.MinValue;

            Assert.AreEqual(j + 1, AddOne(j));
        }

        public static int AddOne(int n)
        {
            int position = 1;

            while (position != 0)
            {
                if ((n & position) == position) {
                    n = n ^ position;
                } else {
                    n = n | position;

                    break;
                }

                position = position << 1;
            }

            return n;
        }
    }
}