VB.NET Core Concepts

Welcome to the core concepts section for Visual Basic .NET (VB.NET). This guide will introduce you to the fundamental principles and building blocks that underpin modern application development with VB.NET on the .NET platform.

What is VB.NET?

Visual Basic .NET (VB.NET) is a high-level, object-oriented programming language developed by Microsoft. It is part of the .NET Framework and .NET Core / .NET 5+, offering a powerful and productive environment for building a wide range of applications, from desktop and web services to mobile apps.

Key Principles

  • Object-Oriented Programming (OOP): VB.NET fully embraces OOP principles like encapsulation, inheritance, and polymorphism, allowing for modular, reusable, and maintainable code.
  • .NET Framework / .NET Core: Applications are built upon the robust .NET runtime, leveraging its extensive class libraries (Base Class Library - BCL) for tasks like file I/O, networking, database access, and UI development.
  • Managed Code: VB.NET code runs under the control of the .NET runtime (CLR - Common Language Runtime), which provides services like automatic memory management (garbage collection), exception handling, and security.
  • Intermediate Language (IL): VB.NET source code is compiled into Intermediate Language (IL), which is then Just-In-Time (JIT) compiled into native machine code by the CLR when the application is executed.

Basic Syntax and Structure

A typical VB.NET program consists of modules, classes, and methods. Here's a simple "Hello, World!" example:


Module HelloWorld
    Sub Main()
        Console.WriteLine("Hello, World!")
    End Sub
End Module

Variables and Data Types

VB.NET supports a rich set of built-in data types:

  • Value Types: Integer (Integer), Floating-Point (Double, Single), Boolean (Boolean), Character (Char), Date (Date), Structures (Structure).
  • Reference Types: Classes (Class), Arrays (Array), Strings (String), Objects (Object).

Variable declaration uses the Dim keyword:

Dim message As String = "Learning VB.NET"

Dim counter As Integer = 0

Control Flow

VB.NET provides standard control flow statements for decision making and looping:

  • Conditional Statements: If...Then...Else, Select Case.
  • Looping Statements: For...Next, For Each...Next, Do While...Loop, Do Until...Loop.

Example: For Loop


For i As Integer = 1 To 5
    Console.WriteLine("Iteration: " & i.ToString())
Next

Object-Oriented Features

VB.NET's strong support for OOP is a cornerstone of its power:

  • Classes and Objects: Define blueprints (classes) for creating instances (objects) with properties and methods.
  • Inheritance: Allow a class to inherit properties and methods from another class.
  • Polymorphism: Enable objects of different classes to respond to the same method call in their own specific ways.
  • Encapsulation: Bundle data (properties) and methods that operate on the data within a single unit (class).

Example: Simple Class


Public Class Person
    Public Property Name As String
    Public Property Age As Integer

    Public Sub Greet()
        Console.WriteLine($"Hello, my name is {Name} and I am {Age} years old.")
    End Sub
End Class

' Usage:
' Dim person1 As New Person()
' person1.Name = "Alice"
' person1.Age = 30
' person1.Greet()

Exception Handling

Robust error handling is crucial. VB.NET uses the Try...Catch...Finally block:


Try
    ' Code that might throw an exception
    Dim result As Integer = 10 / 0 ' This will cause a DivideByZeroException
    Console.WriteLine($"Result: {result}")
Catch ex As DivideByZeroException
    Console.WriteLine($"Error: Cannot divide by zero. {ex.Message}")
Catch ex As Exception
    Console.WriteLine($"An unexpected error occurred: {ex.Message}")
Finally
    Console.WriteLine("Execution finished.")
End Try

Continue exploring other sections to delve deeper into specific VB.NET features and development patterns.