namespace samples {        

    using System;

    using NullableTypes;

    sealed class MyApp {

        static void Main() {

            /*

             * 

             * Definition samples

             * 

             */

            // declaration 

            NullableInt32 ni; 

            // declaration and initialization 

            NullableInt32 nj = 320; 

            // declaration and initialization to Null

            NullableInt32 nk = NullableInt32.Null; 

            /*

             * 

             * Operators and expressions

             * 

             */

            ni = nj * nk;

            Console.WriteLine(" 1) {0}", ni); // -> NullableInt32.Null

            nj *= 11;

            Console.WriteLine(" 2) {0}", nj); // -> 3520

            /*

             * 

             * Assignments and conversions

             * 

             */

            int i = 3200;

            ni = i + 100; // an implicit conversion happen before the assignment

            i = (int)ni;  // this conversion can raise an exception if 'ni' is Null

            Console.WriteLine(" 3) {0}", i); // -> 3300

            /*

             * 

             * Dealing with Null values

             * 

             */

            nk = NullableInt32.Null; // set to null

            nj = 2;

            ni = nk / nj; 

            // Test for Null

            Console.WriteLine(" 4) {0}", ni.IsNull); // -> bool.true

            if (ni.IsNull) 

                Console.WriteLine("    if-true" );  // <-

            else 

                Console.WriteLine("    if-NOT true");

            // Comparison with a Null value return a NullableBoolean.Null,

            // the 'if' will fail (as if false) with a NullableBoolean.Null

            Console.WriteLine(" 6) {0}", (ni > nk));  // -> NullableBoolean.Null

            if (ni > nk)

                Console.WriteLine("    if-true");

            else

                Console.WriteLine("    if-NOT true"); // <-

            // Comparison with a Null value return a NullableBoolean.Null,

            // the 'if' will fail (as if false) with a NullableBoolean.Null

            Console.WriteLine(" 7) {0}", (ni < nk));  // -> NullableBoolean.Null

            if (ni < nk)

                Console.WriteLine("    if-true");

            else

                Console.WriteLine("    if-NOT true"); // <-

            // Getting the Value property raise an exception if the 

            // NullableInt32 variable is Null

            try {

                ni = NullableInt32.Null;

                int k = ni.Value;

            }

            catch (NullableNullValueException ne) {

                Console.WriteLine(" 8) {0}", ne.Message); // -> " Data is Null. This method or property cannot be called on Null values."

            }

            // An explicit conversion to int raise an exception if the 

            // NullableInt32 variable is Null

            try {

                ni = NullableInt32.Null;

                int k = (int)ni;

            }

            catch (NullableNullValueException ne) {

                Console.WriteLine(" 9) {0}", ne.Message); // -> " Data is Null. This method or property cannot be called on Null values."

            }

            return;

        }    

    }

}