The Philosophy of Visual Studio 'NET

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Chapter 1

• The Philosophy of Visual Studio .NET

2
Objectives (1)

• Be introduced to Visual Basic .NET and Visual
  Studio .NET
• Learn about the features of Visual Studio .NET
• Learn how to choose a development language
• Learn about the design and implementation of the
  .NET Framework
• Understand the purpose of the Common Language
  Runtime

3
Objectives (2)

• Receive an introduction to assemblies
• Understand the organization of namespaces
• Understand the .NET Framework class library
• Create a first VB .NET application
• Understand the syntax of Intermediate Language

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Introduction to Visual Basic .NET (1)

• Visual Studio .NET revolutionizes software
  development
• Programs can be developed in any of the four
  Visual Studio .NET languages
• C, C, Visual Basic .NET, Visual J
• Third party languages are also supported
• Each language supplies nearly identical
  functionality
• Each language has the same performance
  characteristics

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Introduction to Visual Basic .NET (2)

• Only the .NET Framework needs to be installed to
  compile and test .NET applications
• Notepad or any text editor will work
• The .NET Framework contains all of the .NET
  compilers and libraries
• Strictly speaking, Visual Studio .NET is not
  required

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Summarizing the New Visual Studio .NET Features
(1)

• All languages share the same integrated
  development environment
• Languages may be selected at install time
• Help system has been reorganized
• Index topics organized by namespaces and types
  within those namespaces
• New controls are supported
• Some VB 6 controls are obsolete
• New types of applications are supported
• ASP.NET, Web Services, Windows Services

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Summarizing the New Visual Studio .NET Features
(2)

• XML is used to communicate information between
  applications and to send and receive data
• New debugging features are supported
• Refer to Appendix A
• Deployment tools have been overhauled
• Deployment accomplished through a new project
  type called a Setup Project

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Language Enhancements

• All Visual Studio .NET languages are
  object-oriented
• True inheritance and polymorphism are supported
• No matter the language, all programs have a
  similar structure
• VB .NET supports several new keywords
• Note that the language has changed considerably
  since VB 6
• C (C-sharp) is a new language
• File structure is similar for all languages
• All programs compiled into Intermediate Language
  (IL)

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Choosing a Development Language

• C is similar to C and may be preferred by C
  developers
• Signed and unsigned types are supported
• Combines syntax and semantics of VB and C
• Strict type checking is optional in VB .NET but
  required by C
• VB .NET supports optional procedure arguments but
  C does not
• C and J have a similar syntax
• Note J is not compatible with Java and does not
  use the Java Virtual Machine

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The Design and Implementation of the .NET
Framework

• The .NET Framework is at the heart of Visual
  Studio .NET
• The .NET Framework defines the rules for language
  interoperability
• The .NET Framework must be installed to compile
  and test any .NET application
• The .NET Framework is installed along with Visual
  Studio .NET
• Available as a free download from Microsoft

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Relationship Between Visual Studio .NET and the
.NET Framework

• Visual Studio .NET provides the Integrated
  Development Environment (IDE)
• Use to develop and test applications
• Visual designers are used to create the interface
  for an application (forms)
• Visual designers are used to manage XML documents
• Other specialized Visual designers exist
• Use Visual Studio .NET to compile and execute
  applications

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Parts of the .NET Framework

• Common Language Runtime (CLR) manages the
  execution of an application
• Memory allocation and memory deallocation
• Just-In-Time (JIT) compiler translates
  Intermediate Language into a native executable
  when executable is run
• .NET Framework class library contains reusable
  components created by the .NET team

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Requirements of the .NET Framework

• The .NET Framework must be installed to develop
  and test any application
• The .NET Framework is installed when installing
  Visual Studio .NET
• The .NET Framework can be downloaded from
  Microsoft
• Runs on all Windows versions except Windows 95
• Limited functionality on Windows 98 and Windows
  ME because of limited operating system support

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.NET Framework Versions

• Two versions
• Desktop version used by Windows 98, Windows 2000,
  and Windows XP
• Compact version used by PDAs and mobile devices
• Microsoft is working with third party vendors to
  work with proprietary operating systems
• Visual Studio .NET 2003 is released
• Almost identical to first version
• Note the project files are not backward compatible

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The Common Language Runtime (CLR)

• Integral part of the .NET Framework
• Services
• Common Type System (CTS) defines standard data
  types and their formats
• Common Language Specification (CLS) defines rules
  for language interoperability
• Just-In-Time (JIT) compiler translates IL into a
  native executable
• Process is called JITting
• CLR manages execution of a running application
• Garbage Collector deallocates memory

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The Common Type System (CTS)

• Defines the primary .NET data types used by all
  applications
• Defines how memory for structures and classes is
  allocated
• Allows components developed in different
  languages to operate together
• Enforces type safety

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The Common Language Specification (CLS)

• A subset of the Common Type System
• Defines rules for naming variables
• Defines primitive data types
• Prohibits unsigned numeric data types
• Supports 0-based arrays
• Specifies rules for function argument lists
• Specifies event rules
• Prohibits memory pointers and pointers to
  functions
• A limited form of function pointers are supplied
  through delegates

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Intermediate Language (IL)

• .NET is designed to work with different hardware
  architectures
• Conceptually, an application can run on any
  computer
• All programs are compiled into a machine
  independent Intermediate Language (IL)
• Format is similar to assembly language but is
  hardware independent
• Just-In-Time compiler translates IL into a native
  executable
• Conceptually, the process is similar to the Java
  Virtual Machine

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Execution Management

• Code executed by the CLR is called managed code
• One application cannot interfere with the memory
  allocated to another application

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Execution Management
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Introduction to the Garbage Collector (GC)

• CLR performs memory management
• A contiguous area of memory allocated to a
  process is called the managed heap
• Reference types are allocated from the managed
  heap
• CLR reclaims memory using the Garbage Collector
  (GC)
• GC examines variables to reclaim unused memory
• Looks for memory without a corresponding variable
  (root)
• GC uses 3 generations to optimize performance
• Allocated memory propagated from generation 0 to
  generation 1 to generation 2

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Introduction to Assemblies

• IL files have a well-defined format called an
  assembly
• Assemblies are the primary physical building
  blocks of an application
• Every application is considered an assembly
• .NET Framework classes are stored in assemblies
• Assemblies are a special form of executable file
• DLL files are assemblies too

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Assembly Contents

• The assembly manifest contains a description of
  the assembly
• Manifest referred to as metadata
• Manifest contains
• A descriptive name and localization information
  are called the assembly identity
• Assembly contents describe the types exposed by
  the assembly
• Dependencies reference other assemblies required
  for the current assembly to operate
• Permissions dictate who can use the assembly
• Both users and other processes

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Common Assemblies

• System.dll defines the primary data types
• System.Data.dll defines the components that make
  up ADO.NET
• System.Drawing.dll contains the components used
  to draw various shapes to an output device
• Forms and printers are output devices
• System.Windows.Forms.dll contains components to
  implement desktop forms
• System.XML.dll is used to process XML documents

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The Organization of Namespaces

• Assemblies are physical Namespaces are logical
• An assembly may contain one or more namespaces
• Namespaces are organized into a hierarchy
• Namespaces are connected together with a dot (.)
• The System namespace contains components
  developed by the .NET team
• The Microsoft namespace contains components
  developed by Microsoft but outside of the .NET
  development team
• Microsoft.VisualBasic for example

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Common Namespaces

• System namespace contains fundamental classes
• System.Data namespace contains classes supplying
  data access capabilities
• ADO.NET
• System.Drawing provides access to the Graphical
  Device Interface allowing shapes to be drawn to
  forms and printers
• System.IO provides access to files
• System.Windows.Forms supplies the capabilities to
  create forms and control instances on those forms

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Introduction to Types

• Types are divided into two categories
• Value types store data directly in the variable
• Int32, Int64, Single, Double for example
• Reference types store a memory address in the
  variable
• A memory address points to the address of the
  actual object
• Object memory allocated from the managed heap
• String, Array

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Namespace Contents (1)

• Classes
• Reference types
• Support fields, events, methods, and properties
• Delegates
• Reference types
• Delegates provide event support
• Structures
• Value types
• Support properties and methods
• Conceptually similar to VB 6 user-defined types

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Namespace Contents (2)

• Enumerations
• Limited form of a value type
• Associate a mnemonic name with a constant value
• Many object properties are enumerations
• Interfaces
• Define members that other classes implement
• Interfaces define the task a class must perform
  but not how to perform that task

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Relationship Between Types
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The System.Console Class

• Definition
• Use to read and write characters or lines from a
  system console (Command Prompt window)
• Methods
• Read method reads a character from the input
  stream
• ReadLine method reads a line from the input
  stream
• Line contains one or more characters
• Carriage return character at the end of line is
  removed
• Write method writes a character to an output
  stream
• WriteLine method writes a line to the output
  stream
• Line is terminated with a carriage return
  character

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The System.Console Class (Example)

• Read a character
• pintCharacter System.Console.Read()
• Read a line
• pstrLine System.Console.ReadLine()
• Write a string
• System.Console.Write("Course Technology")
• Write a string terminated by a carriage return
• System.Console.WriteLine("Course Technology")

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The .NET Framework Class Library (Introduction)

• Contains all types defined by the .NET Framework
• All classes, delegates, enumerators, interfaces,
  and structures are types
• Types are created from other types using
  inheritance
• All types ultimately derive from the superclass
  named System.Object

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The .NET Framework Class Library (Organization)
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Members of System.Object

• A constructor is a procedure named New that
  executes when the CLR creates a class instance
• Equals tests whether two objects contain the same
  data
• GetHasCode defines the hashing function
• GetType returns the data type of the object
• ReferenceEquals tests for reference equality
• ToString converts the object's value to a String
• By default, ToString returns the fully qualified
  name of a class

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Primary .NET Framework Data Types
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Declaring a Variable

• Use an access modifier, followed by the variable
  name, followed by the data type
• Example
• Dim pintCurrent As System.Int32
• Dim pintCurrent As Integer
• The preceding statements are equivalent
• The first uses the formal syntax and the later
  uses convenience syntax
• Both declare an Integer variable named pintCurrent

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Type Inheritance

• Every type is inherited from another type
• Ultimately, all types inherit from System.Object
  (the superclass)
• System.ValueType inherits from System.Object
• System.Int32 inherits from System.ValueType
• System.Array (reference type) inherits from
  System.Object directly
• System.String (reference type) inherits from
  System.Object directly

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Type Inheritance (Illustration)
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The Implementation of Structures

• Structures have methods and fields
• Int32 has fields named MinValue and MaxValue
  storing minimum and maximum possible values
• Example
• pintMin System.Int32.MinValue()
• pintMax System.Int32.MaxValue()
• pstrMin pintMin.ToString()
• pstrMax pintMax.ToString()

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Type Conversion (1)

• Converting data from one type to another is
  called type conversion
• Using implicit type conversion, VB .NET will
  attempt to convert one type to another
  automatically
• Using explicit type conversion, VB .NET will
  automatically convert more restrictive types to
  less restrictive types but not the other way
  around
• Option Strict statement enables or disables
  strict type checking
• Option Strict On
• Option Strict Off

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Type Conversion (2)

• Integer will implicitly convert to Long because
  Long is less restrictive
• Single will implicitly convert to Double because
  Double is less restrictive
• Integer will implicitly convert to Single or
  Double

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The System.Convert Class

• Use the methods of the System.Convert class to
  perform explicit type conversion
• ToBoolean converts to a Boolean value
• ToDateTime converts to a DateTime structure
• ToInt16 converts to a Short Integer
• ToInt32 converts to an Integer
• ToInt64 converts to a Long Integer
• ToSingle converts to a single precision number
• ToDouble converts to a double precision number
• ToString converts to a string

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The System.Convert Class (Example)

• Read a line and convert the contents to an
  Integer (Int32)
• Note that an error will occur if the value cannot
  be converted
• Dim pstrCurrent As String
• Dim pintCurrent As Integer
• pstrCurrent System.Console.ReadLine()
• pintCurrent System.Convert.ToInt32(pstrCurrent)

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The System.Math Class

• Fields
• E represents the natural logarithmic base
  specified by the constant e
• PI stores the value of Pi
• Methods
• Abs returns the absolute value of its argument
• Cos returns the cosine of an angle
• Sign indicates whether the argument is positive
  or negative
• Sin returns the sine of an angle
• Sqrt returns the square root of an argument
• Tan returns the tangent of an angle

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Organization of System.Convert and System.Math
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Creating a First Application

• A program can be created in a module block
  beginning with the Module and End Module
  keywords, respectively
• Statements appear between the Module and End
  Module keywords
• Example
• Module Startup01
• ' Statements
• End Module

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Creating a Startup Procedure

• VB .NET executes a sub procedure named Main when
  a program starts
• Example
• Module Startup01
• Public Sub Main()
• ' Statements
• End Sub
• End Module

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Locating the Visual Basic .NET Compiler

• The compiler is not stored in a searchable path
  by default
• Copy the script named corvars.bat to a searchable
  path
• Use vsvars.bat for .NET 2003
• Execute the script to reset the path as necessary

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Running Corvars.bat
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Compiling a Visual Basic .NET Application

• The compiler uses a command line interface
• Flags control compiler options
• /debug enables debugging
• /libpath specifies a directory to search for
  assemblies
• /main specifies the class or module containing
  Sub Main
• /optionexplicit enforces explicit variable
  declaration
• /optionstrict enforces strict type checking
• /out - defines executable file name
• /reference makes an assembly available
• /verbose displays compiler information

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Compiling a Visual Basic .NET Application
(Example)
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Executing the Application
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The Syntax of Intermediate Language

• All programs are compiled to IL format
• ILDasm.exe can be run from a Command Prompt
  window to produce a disassembled output file
• A graphical interface is also supported
• Command Prompt Example
• ILDasm Startup01.exe /OutStartup01.il

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ILDasm in a Window
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ILDasm displaying Manifest