Understanding Properties and Methods

Welcome to the next lesson! In this lesson, you’ll learn about properties and methods, their purpose, and how to use them effectively in C#. Let’s get started!

What Are Properties?

Properties provide a way to encapsulate and control access to a class’s fields. They use get and set accessors to retrieve and modify field values.

Example: Properties ensure that the field data is validated or computed dynamically.

Using Properties

Properties are often used to validate or process data before assigning it to a field or returning its value. Example:

using System;

class Person {
    private int age;

    public int Age {
        get { return age; }
        set {
            if (value > 0) {
                age = value; // Only assign valid ages
            } else {
                Console.WriteLine("Age must be positive.");
            }
        }
    }
}

class Program {
    static void Main() {
        Person person = new Person();
        person.Age = 25; // Valid value
        Console.WriteLine("Age: " + person.Age);

        person.Age = -5; // Invalid value
    }
}

Auto-Implemented Properties

For simple cases, you can use auto-implemented properties. Example:

Tip: Auto-implemented properties simplify the code when no additional logic is needed.

using System;

class Car {
    public string Model { get; set; }
    public string Color { get; set; }
}

class Program {
    static void Main() {
        Car car = new Car { Model = "Sedan", Color = "Blue" };
        Console.WriteLine("Model: " + car.Model + ", Color: " + car.Color);
    }
}

What Are Methods?

Methods define the behavior of a class. They are blocks of reusable code that perform specific tasks, improving code modularity and readability.

Example: A method could calculate the area of a rectangle or print a greeting message.

Defining and Calling Methods

To define a method, specify the return type, method name, and optional parameters. Example:

Key Point: Methods can return values or perform actions without returning anything (void).

using System;

class Calculator {
    public int Add(int a, int b) {
        return a + b; // Adds two numbers
    }
}

class Program {
    static void Main() {
        Calculator calc = new Calculator();
        int result = calc.Add(10, 5); // Call the method
        Console.WriteLine("Sum: " + result);
    }
}

Methods with Parameters

Methods can accept parameters to operate on different values. Example:

Tip: Parameters allow you to pass data into methods for greater flexibility.

using System;

class Greeter {
    public void Greet(string name) {
        Console.WriteLine("Hello, " + name + "!");
    }
}

class Program {
    static void Main() {
        Greeter greeter = new Greeter();
        greeter.Greet("Alice");
        greeter.Greet("Bob");
    }
}

Practice Challenge

Create a class called Rectangle with properties Length and Width, and a method CalculateArea() that returns the area of the rectangle. Example:

using System;

class Rectangle {
    public int Length { get; set; }
    public int Width { get; set; }

    public int CalculateArea() {
        return Length * Width;
    }
}

class Program {
    static void Main() {
        Rectangle rect = new Rectangle { Length = 5, Width = 4 };
        Console.WriteLine("Area: " + rect.CalculateArea());
    }
}

Great Job!

Congratulations! You’ve learned how to define and use properties and methods to encapsulate and add functionality to your classes. In the next lesson, we’ll explore constructors and learn how to initialize objects effectively. Let’s keep coding!