
Delve into .NET development with C#, covering programming fundamentals, object-oriented principles, exception handling, and multithreading. Gain hands-on experience to build cross-platform applications effectively.

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.NET is Microsoft’s free and open source framework for developing native software applications on Linux, macOS, and Windows. The power of cross-platform development allows developers to design, code, and run programs on a wide array of platforms.

This course is an introduction to developing .NET applications using C#. You’ll start start with a comprehensive review of C# and computer programming fundamentals: data types, conditionals, loops, methods, and more. You’ll then review the basics of object-oriented programming before diving into methods, exception handling, delegation, and events. With this foundation, you’ll continue building interfaces, collections, database operations, and multithreading. You’ll wrap up with process improvements using dynamic binding, garbage collection, and unmanaged resources.

By the end of this course, you’ll have hands-on experience with C# and .NET, and be ready to build applications using object-oriented programming principles on almost any platform.

Mastering C# and .NET

# Introduction

Most objects used in C# programs are managed code. Such objects are managed by the CLR and are easily cleaned by the garbage collector. There are also objects that involve unmanaged resources, however (connections to files, databases, network connections, and so on). These unmanaged objects access the operating system APIs. The garbage collector can handle managed objects, but it doesn’t know how to dispose of unmanaged resources. In these cases, we must implement the cleanup means by ourselves.

The release of unmanaged resources implies the implementation of one of two mechanisms: creation of a destructor or implementation of the `IDisposable` interface
 
# Destructors

Constructors are used to create an instance of a class. **Destructors**, on the other hand, contain instructions on what happens when an instance gets destroyed (by the garbage collector). Destructors:

 - Can only be defined in classes.
 - Can’t have access modifiers or parameters.
 - Can’t be inherited or overridden.


> **Note:** Each class can only have one destructor.

A destructor method has a class name (like a constructor) preceded by a tilde sign (`~`):

```C#
class Car
{
	// Constructor
	public Car()
	{
	}

	// Destructor
	~Car()
	{
		// Instructions to release unmanaged resources
	}
}
``` 

When compiled, our `~Car()` destructor is converted to a code similar to the following:

```C#
protected override void Finalize()
{
	try
	{
		// Instructions to release unmanaged resources
	}
	finally
	{
		base.Finalize();
	}
} 
```

The garbage collector calls the `Finalize()` method when removing the object from memory. We can’t override the `Finalize()` method manually, so we must create a destructor instead. The `Finalize()` method is defined in the `System.Object` class.

# Call the destructor

For demonstration purposes, let's put a simple `Console.WriteLine()` statement inside the destructor. Observe when the destructor is called:

Create destructors for user-defined types.

Getting Started

C# Programming Basics

Classes and OOP

Classes and OOP II

Exception Handling

First Assessment

Delegates and Events

Interfaces

Additional Features

Collections

LINQ

Working with Strings

Working with Dates and Time

Multithreading and Asynchronous Programming

Reflection

Dynamic Binding

Garbage Collection and Unmanaged Resources

Final Assessment

Next Steps

Appendix

Finalizers

Introduction