C# - STRUCTURES:-
- In C#, a structure is a value type data type. It helps you to make a sing le 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
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 would declare the Book structure:
struct Books
{
public string title;
public string author;
public string subject;
public int book_id;
};
Thefollowing prog ram shows the use of the structure:
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;
/* 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();
}
When the above code is compiled and executed, it produces the following result:
Book 1 title : C Programming
Book 1 author : Nuha Ali
Book 1 subject : C Programming Tutorial
Book 1 book_id : 6495407
Book 2 title : Telecom Billing
Book 2 author : Zara Ali
Book 2 subject : Telecom Billing Tutorial
Book 2 book_id : 6495700
Features of C# Structures
- Structures can have methods, fields, indexers, properties, operator methods, and events.
- Structures can have defined constructors, but not destructors. However, you cannot define a default constructor for a structure. Thedefault constructor is automatically defined and can't be changed.
- Unlike classes, structures cannot inherit other structures or classes.
- Structures cannot be used as a base for other structures or classes.
- A structure can implement one or more interfaces.
- Structure members cannot be specified as abstract, virtual, or protected.
- When you create a struct object using the New operator, it gets created and the appropriate constructor is called. Unlike classes, structs can be instantiated without using the New operator.
- If the New operator is not used, the fields will remain unassig ned and the object cannot be used until all the fields are initialized.
Class vs Structure
- classes are reference types and structs are value types
- structures do not support inheritance
- structures cannot have default constructor
In the light of the above discussions, let us rewrite the previous example:
using System;
struct Books
{
private string title;
private string author;
private string subject;
private int book_id;
public void getValues(string t, string a, string s, int id)
{
title = t;
author = a;
subject = s;
book_id = id;
}
public void display()
{
Console.WriteLine("Title : {0}", title);
Console.WriteLine("Author : {0}", author);
Console.WriteLine("Subject : {0}", subject);
Console.WriteLine("Book_id :{0}", book_id);
}
};
public class testStructure
{
public static void Main(string[] args)
{
Books Book1 = new Books(); /* Declare Book1 of type Book */
Books Book2 = new Books(); /* Declare Book2 of type Book */
/* book 1 specification */
Book1.getValues("C Programming",
"Nuha Ali", "C Programming Tutorial",6495407);
/* book 2 specification */
Book2.getValues("Telecom Billing",
"Zara Ali", "Telecom Billing Tutorial", 6495700);
/* print Book1 info */
Book1.display();
/* print Book2 info */
Book2.display();
Console.ReadKey();
}
}
When the above code is compiled and executed, it produces the following result:
Title : C Programming
Author : Nuha Ali
Subject : C Programming Tutorial
Book_id : 6495407
Title : Telecom Billing
Author : Zara Ali
Subject : Telecom Billing Tutorial
Book_id : 6495700
C# - ENUMS:-
- An enumeration is a set of named integer constants. An enumerated type is declared using the enum keyword.
- C# enumerations are value data type. In other words, enumeration contains its own values and cannot inherit or cannot pass inheritance.
Declaring enum Variable
The general syntax for declaring an enumeration is:
enum <enum_name>
{
enumeration list
};
Where,
- Theenum_name specifies the enumeration type name.
- Theenumeration list is a comma-separated list of identifiers.
Each of the symbols in the enumeration list stands for an integ er value, one g reater than the symbol that
precedes it. By default, the value of the first enumeration symbol is 0. For example:
enum Days { Sun, Mon, tue, Wed, thu, Fri, Sat };
Example:
Thefollowing example demonstrates use of enum variable:
using System;
namespace EnumApplication
{
class EnumProgram
{
enum Days { Sun, Mon, tue, Wed, thu, Fri, Sat };
static void Main(string[] args)
{
int WeekdayStart = (int)Days.Mon;
int WeekdayEnd = (int)Days.Fri;
Console.WriteLine("Monday: {0}", WeekdayStart);
Console.WriteLine("Friday: {0}", WeekdayEnd);
Console.ReadKey();
}
}
}
When the above code is compiled and executed, it produces the following result:
Monday: 1
Friday: 5