Visual Basic.NET Comprehensive Concepts and Techniques What’s new in VB.NET adapted from a presentation on Introduction to Visual Basic.NET by Jeff Quasney

Visual Basic .NETComprehensive Concepts

and Techniques

What’s new in VB .NETadapted from a presentation on

Introduction to

Visual Basic .NET

by

Jeff Quasney

Course Technology

2Introduction to Visual Studio .NET


An Overview


What’s New in Visual Studio .NET?

• IDE (Start page, common for ALL .NET languages)

• Application templates• New editing tools (HTML, XML, XSL,

CSS…)• Cross-language debugging, Multiple

languages per “Solution”• New sample apps and documentation• Strong focus on XML


What’s New in Microsoft Visual Basic .NET?• VB .NET was a rewrite, not an update

• New/changed data types– No Variant, CTS

• New/changed syntax– Dim, assignment, arrays, keywords…

• Application distribution


What’s New in Microsoft Visual Basic .NET? (continued)• Inheritance• Exception handling (Structured exception

handling)• Overloading• Multithreading• Web development

– Web services– Web applications (ASP.NET)

• ADO.NET


Application Types

• Console Applications


Application Types

• Windows Applications


Application Types

• Windows Services


Application Types

• Web Applications


Application Types

• Web Services


Application Types

• Components


What is .NET?


.NET Framework


Why .NET?

• Common classes

• Common security model– DLL “H E double-toothpicks” gone?– Side-by-side execution

• Garbage collection

• Multi-platform?

• New application types

• Language interoperability


The Common Language Runtime

• Takes control of the application and runs the application under the operating system

• Microsoft Intermediate Language (MSIL)



• MSIL is CPU/OS independent

• Compile once for multiple CPU’s/platforms– Take an EXE and run it on Linux– Ximian (?) is working on this

• Assembly and manifest concept– Xcopy installs– Side-by-side execution– Logically, all EXEs and DLLs act as DLLs



• Registration info no longer in registry– Meta data stored in assemblies– Only distribute assembly

• .NET Framework required on user’s system

• Memory management• Exception handling• No IDL, no registration, no HRESULTS, no

GUIDs, • Replaces all COM plumbing


What’s New in VB .NET?


About Procedures• Subs and functions need parentheses

Use

MyProc(“A parameter”)

Not

MyProc “A parameter”

• ByVal is now the default!• Optional arguments need a default value

– Sub DoWork(Optional ByVal i As Integer = 1)

• Return is used in Functions to return a value


About IF Statements

• AndAlso and OrElse do short-circuiting

If intX = 1 AndAlso intY = 2 Then

In above example, second expression is not evaluated if intX is not 1


About Object Declarations

• OLDDim objCustomer As Store.CustomerSet objCustomer = New Store.Customer

• NEWImports StoreDim objCustomer = New Customer

ORDim objCustomer as Customer = New Customer


About Scope

• New Block-level ScopeDim intX As Integer

For intX = 1 To 5

Dim intZ As Integer

MessageBox.Show(“Scope is important.”)

Next intX

MessageBox.Show(“intZ is out of scope!”)


About Arrays• Lower bound is always zero

– Dim intA(5 To 8) no longer is possible– Option Base is gone as well

• Arrays have VERY useful methods• Declare arrays by upperbound, not size – Same

as VB6– Dim strX(10) As String contains 11 elements

• Setting an array to another array is now done by reference– In VB6, this was done by value– Use Copy method of arrays to make an actual copy


About Loops

• While…Wend changed to While…End While


About Data Types• All variables are objects. Variants are gone.• Type a period after any variable in the IDE to

see methods/properties• Strings are never fixed length. They are

destroyed and recreated by the CLR when value changes– Only one type of string variable for ALL languages

• No Currency data type. Now decimal.• UDTs are gone

– Use structures instead• Structure statement replaces Type• Structures support methods!


Useful Options

• Option Strict On– Forces declarations– Forces data types to be same on both sides

of =– Use it always. Get in the habit. Force your

students to use it in assignments.


About Operators

• New concatenation operators+, -, *, /, &

intI += 100

intl -= 100


About Controls

• Default properties of controls are GONE

• New way to set tab order

• Shape controls are gone– Use System.Drawing namespace


About Menus and Help

• Menu editor– Create a menu and a context menu

• Help– Dynamic help is addictive


Misc

• New control alignment tools • New properties

– Anchoring and AutoSize– Opacity of forms

• Printing– Several new, powerful printing controls– Print controls/objects get more complicated, but more

powerful– Crystal Reports is included with

Professional/Academic versions• New way to set tab order


What’s new in OO?

• Too much to mention• Inheritance• Polymorphism• New syntax for creating properties• Read-only, Write-only properties• Aggregation is weird, though (just in VB)• Constructor = Sub New() : Destructor = Sub

Finalize()– Don’t assume you know when destructor is called


What’s new in Databases?

• Too much to mention

• ADO.NET

• SqlClient namespace vs. OleDB namespace

• DataSet and DataTable

• DataReader

• Plea/Editorial: Please don’t use Data controls


What will make you scratch your head?• Line numbers are messed up

• Can’t print a form in design mode for a Windows form, but you CAN for a Web form

• Value of True (non-zero, not 1)

Visual Basic .NETComprehensive Concepts

and Techniques

The End

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Visual Basic.NET Comprehensive Concepts and Techniques What’s new in VB.NET adapted from a presentation on Introduction to Visual Basic.NET by Jeff Quasney