C# coding notes

C# Programming
Classes
 A blueprint for a specific object.
 Collection of objects of similar type.
 Model for creating objects.

Objects
 template/blueprint that describes the behaviour/state that an object of its type support
 Instance of a class
 Process of creating an object = instantiation
 Fields are actual variables in your object that stores a particular piece of information.
 The data and the methods are called members of an object.
 Communicate through methods
 Creating an object means allocating memory to store the data of variables temporarily
 State is stored in fields and behaviour is stored in methods
 Classes are the Nouns in your analysis of the problem
 Methods in an class correspond to the Verbs that the noun does
 Properties are the Adjectives that describe the noun

Abstraction
 hide the implementation details and display only essential features of the object
 Once a class has been declared as an Abstract class, it cannot be instantiated; it means the object of that class cannot be
created.




Encapsulation
 variables of a class will be hidden from other classes, and can be accessed only through the methods of their current class
 let’s you control the data and operations within a class that are exposed to other classes
 To encapsulate declare the variables of a class as private
 Fields are like variables because they can be read or set directly, subject to applicable access modifiers
 Properties have get and set accessors, which provide more control on how values are set or returned. (read-write property)
 If you don’t want the user to change the value do not add a set property = read-only
 Property without get accessor = write-only
 Private field = public property (normally)
Eg.
class Person
{
private string name; // field

public string Name // property
{
get { return name; } // get method
set { name = value; } // set method
}
}

, Enumeration
 Special class that represents a group of constants
Eg. class Program
{
Private Gender gender;
{
Public enum Gender
{
Male;
Female;
}
gender = Gender.Female;


Constructors
 special type of method that’s executed when an object is instantiated
 enable the programmer to set default values, limit instantiation, and write code that is flexible and easy to read




Instantiating a class
 objects created at runtime from a class are called instances of that particular class

Inheritance
 allows one to create new classes that reuse, extend and modify the behaviour that is defined in other classes.
 Class whose members are inherited = base class/ parent class
 Class that inherits those members = derived class/ child class
 A derived class can only have one base class
 Derived class is a specialization of the base class
 Derived class gains all the members of the base class except its constructors and destructors
 Derived class can reuse the code in the base class without having to re-implement it.
 Derived class can add more members
 Derived class extends the functionality of the base class
 Eg. public class Circle:Shape (Shape is the base class)
 If you define a constructor in the base or derived class you should do the same in the opposite

Polymorphism
 Occurs when we have many classes related to eachother by inheritance
 Uses the methods from Inheritance to perform different tasks, which allows one to perform a single action in different ways.
 Static polymorphism: