1. Enum,Structure and Nullable Types Ashima Wadhwa

2. Enumerations, Enumerations, or enums, are used to group named constants similar to how they are used in C and C++; they are available in Java beginning in Version 1.5. In C#, enums are value types, and enum constants must be integral numeric values. The ToString method can be used to print out string representations of the named constants.

3. The following example defines a simple Color enumeration in C#. public enum Color { Green, //defaults to 0 Orange, //defaults to 1 Red, //defaults to 2 Blue //defaults to 3 }

4. public enum Color2 { Green = 10, Orange = 20, Red = 30, Blue = 40 }

5. class TestEnums { static void Main() { System.Console.WriteLine("Possible color choices: "); //Enum.GetNames returns a string array of named constants for the enum. foreach(string s in System.Enum.GetNames(typeof(Color))) { System.Console.WriteLine(s); } Color favorite = Color.Blue; System.Console.WriteLine("Favorite Color is {0}", favorite); System.Console.WriteLine("Favorite Color value is {0}", (int) favorite); }

6. Structure In C#, a structure is a value type data type. It helps you to make a single variable hold related data of various data types. The struct keyword is used for creating a structure. Structures are used to represent a record. Suppose you want to keep track of your books in a library. You might want to track the following attributes about each book: – Title – Author – Subject – Book ID

7. Defining a Structure To define a structure, you must use the struct statement. The struct statement defines a new data type, with more than one member for your program. – For example, here is the way you can declare the Book structure:

8. using System; struct Books { public string title; public string author; public string subject; public int book_id; }; public class testStructure { public static void Main(string[] args) { Books Book1; /* Declare Book1 of type Book */ Books Book2; /* Declare Book2 of type Book */ /* book 1 specification */ Book1.title = "C Programming"; Book1.author = "Nuha Ali"; Book1.subject = "C Programming Tutorial"; Book1.book_id = 6495407;

9. /* book 2 specification */ Book2.title = "Telecom Billing"; Book2.author = "Zara Ali"; Book2.subject = "Telecom Billing Tutorial"; Book2.book_id = 6495700; /* print Book1 info */ Console.WriteLine( "Book 1 title : {0}", Book1.title); Console.WriteLine("Book 1 author : {0}", Book1.author); Console.WriteLine("Book 1 subject : {0}", Book1.subject); Console.WriteLine("Book 1 book_id :{0}", Book1.book_id); /* print Book2 info */ Console.WriteLine("Book 2 title : {0}", Book2.title); Console.WriteLine("Book 2 author : {0}", Book2.author); Console.WriteLine("Book 2 subject : {0}", Book2.subject); Console.WriteLine("Book 2 book_id : {0}", Book2.book_id); Console.ReadKey(); }

10. Nullable Types C# provides a special data types, the nullable types, to which you can assign normal range of values as well as null values. For example, you can store any value from - 2,147,483,648 to 2,147,483,647 or null in a Nullable variable. Similarly, you can assign true, false, or null in a Nullable variable. Syntax for declaring a nullable type is as follows:

11. using System; namespace CalculatorApplication { class NullablesAtShow { static void Main(string[] args) { int? num1 = null; int? num2 = 45; double? num3 = new double?(); double? num4 = 3.14157; bool? boolval = new bool?(); // display the values Console.WriteLine("Nullables at Show: {0}, {1}, {2}, {3}", num1, num2, num3, num4); Console.WriteLine("A Nullable boolean value: {0}", boolval); Console.ReadLine(); }

12. When the above code is compiled and executed, it produces the following result: Nullables at Show:, 45,, 3.14157 A Nullable boolean value:

13. Queries??