public class Customer
{
   // Fields, properties, methods and events go here...
}
Customer customer = new Customer();


// Class inheritance
public class Manager : Employee
{
    // Employee fields, properties, methods and events are inherited
    // New Manager fields, properties, methods and events go here...
}


// Abstract Class
public abstract class A
{
    public abstract void DoWork(int i);
}
public class B : A
{
    public override void DoWork(int i)
    {
        // implementation.
    }
}


// Sealed class => can not be inherited (String is sealed class)
public sealed class D
{
    // Class members here.
}


// Partial Classes
public partial class Employee
{
    public void DoWork()
    {
    }
}

public partial class Employee
{
    public void GoToLunch()
    {
    }
}

// If you don't provide a constructor for your struct, 
// C# relies on an implicit parameterless constructor to automatically initialize each field to its default value.
public class Person {
   private string name;
   public Person(string name){
      self.name = name;
   }
   // ... ... ...
}

// expression body definition ctor
public class Location {
   public string Name { get; set; } 
   public Location(string name) => Name = name;
}


// resuing ctor: this()
public class Employee {
    public int Salary;
	
    public Employee(int annualSalary){
        Salary = annualSalary;
    }
	
    public Employee(int weeklySalary, int numberOfWeeks){
        Salary = weeklySalary * numberOfWeeks;
    }
}
public class Employee {
    public int Salary;
	
    public Employee(int annualSalary){
        Salary = annualSalary;
    }
	
    public Employee(int weeklySalary, int numberOfWeeks) : this(weeklySalary * numberOfWeeks) { }
}


// base ctor: base()
public class Manager : Employee {
    public Manager(int annualSalary) : base(annualSalary) {
        //Add further instructions here.
    }
}

public class Adult : Person {
   private static int minimumAge;
   static Adult() {
      minimumAge = 18;
   }
}
public class Child : Person {
   private static int maximumAge;
   static Child() => maximumAge = 18;
}

// Property
// following property has backing field and does data sanitization/validation
class TimePeriod {

   private double _seconds;

   public double Hours {
   
       get { return _seconds / 3600; }
	   
       set { 
            if (value < 0 || value > 24) {
                throw new ArgumentOutOfRangeException($"{nameof(value)} must be between 0 and 24.");
            }
			
            _seconds = value * 3600; 
       }
   }
}

// Expression body definitions
public class Person {
   public string Name => $"{_firstName} {_lastName}";   
}

// get and the set accessor can be implemented as expression-bodied members
public string Name {
    get => _name;
    set => _name = value;
}

// Auto-implemented properties 
// => when get and set accessors just assign a value to or retrieve a value from a backing field without including any additional logic
class Person {
    public string Name { get; set; }
    public string Foo { get; set; } = string.Empty;
}

// Restricting Accessor Accessibility
class Person {
    public string FirstName { get; private set; }          
}


// Get only accessor
class Person {
    private string _name;            // the name field
    public string Name => _name;     // the Name property            
}
public class Measurements {
    public ICollection<DataPoint> points { get; } = new List<DataPoint>();
}

// Hiding property from parent class using new keyword
public class Foo {
    public new string Name {get; set;}
}



// Field
public class Foo
{
    // private field
    private DateTime date;

    // public field (Generally not recommended.)
    public string day;
	
    private string otherDay = "";
}

public class Person
{
    public string FirstName { get; set; }

    public string LastName { get; set; }

    private string fullName;
    public string FullName
    {
        get
        {
            if (fullName == null)
                fullName = $"{FirstName} {LastName}";
            return fullName;
        }
    }
}

public class Cat {
    // Auto-implemented properties.
    public int Age { get; set; }
    public string Name { get; set; }

    public Cat() {
    }

    public Cat(string name) {
        this.Name = name;
    }
}
Cat cat = new Cat { Age = 10, Name = "Fluffy" };
Cat sameCat = new Cat("Fluffy"){ Age = 10 };



// setting indexer in object intialiser
public class Foo {
  private var binary = new string[2];
  
  public string this[int i] {
    get { return items[i]; }
    set { items[i] = value; }
  }
}
var foo = new Foo { [0] = "zero", [1] = "one" };



// Object Initializers with anonymous types
var pet = new { Age = 10, Name = "Fluffy" };
/*
Although object initializers can be used in any context, they are especially useful in LINQ query expressions. 
Query expressions make frequent use of anonymous types, which can only be initialized by using an object initializer, 
as shown in the following declaration.
*/
var productInfos =
    from p in products
    select new { PName = p.ProductName, PPrice = p.UnitPrice };
	
foreach(var p in productInfos){
	var name = p.PName
	var price = p.PPrice
	// ...  ... ...
}