Session 4: In-Depth Explanation

Lecture Topics:

• Static Members of a Class
  • Fields
  • Methods
  • Properties
  • Constructors
• Static Classes
• Static Local Functions
• Inheritance
  • Access Specifiers
  • Constructors in a Hierarchy
  • Overloading in Derived Class
  • Hiding, using new
  • override
  • Sealed Methods
• Abstract Classes
• Abstract Methods
• Sealed Classes

Lab:

• Create multiple classes that use Inheritance based concepts.

Lecture: Detailed Explanation

1. Static Members of a Class

Static members belong to the class itself rather than an instance, shared across all instances of the class.

• Static Fields:

  • Shared data accessible without instantiating the class.

  • Example:

    public class Employee
    {
        public static int EmployeeCount; // Shared field
        public string Name { get; set; }
        public Employee() => EmployeeCount++; // Increment on creation
    }
    Employee emp1 = new Employee();
    Employee emp2 = new Employee();
    Console.WriteLine(Employee.EmployeeCount); // Outputs: 2
    
    

• Static Methods:

  • Methods that don’t require an instance, often used for utility functions.

  • Example:

    public class Calculator
    {
        public static int Add(int a, int b) => a + b;
    }
    Console.WriteLine(Calculator.Add(5, 3)); // Outputs: 8
    
    

• Static Properties:

  • Properties that belong to the class, not instances.

  • Example:

    public class Settings
    {
        private static string _companyName = "Acme Corp";
        public static string CompanyName
        {
            get => _companyName;
            set => _companyName = value;
        }
    }
    Settings.CompanyName = "New Corp";
    Console.WriteLine(Settings.CompanyName); // Outputs: New Corp
    
    

• Static Constructors:

  • Initialize static members, called automatically before any static member is accessed.

  • Example:

    public class Logger
    {
        public static string LogFilePath;
        static Logger()
        {
            LogFilePath = "log.txt";
            Console.WriteLine("Static constructor called");
        }
    }
    Console.WriteLine(Logger.LogFilePath); // Outputs: Static constructor called, log.txt