microsoft visual basic 2010: reloaded fourth edition

Microsoft Visual Basic 2010: Reloaded Fourth Edition

Chapter OneAn Introduction to Visual Basic 2010

Microsoft Visual Basic 2010: Reloaded, Fourth Edition 2

Objectives

After studying this chapter, you should be able to:• Create a Visual Basic 2010 Windows-based

application• Manage the windows in the Integrated Development

Environment (IDE)• Set the properties of an object• Add a control to a form• Use the Label, Button, and PictureBox tools• Use the options on the Format menu


Objectives (cont'd.)

• Enter code in the Code Editor window• Save a solution• Start and end an application• Print an application’s code and interface• Write an assignment statement • Print an application’s code and interface• Close and open an existing solution• Find and correct a syntax error

Visual Studio 2010

• Visual Basic 2010 is an object-oriented programming language– Object: anything that can be seen, touched, or used– Class: a pattern used to create an object– Instance: an object created from a class; object is

said to be instantiated

• Integrated Development Environment (IDE):– Contains all the tools and features needed to create,

run, and test programs– Includes Visual Basic, Visual C++, Visual C#, and

Visual F#



Visual Studio 2010 (cont'd.)

• Application: program or suite of programs

• Windows-based application: – Has a Windows user interface – Runs on a personal computer

• User interface: what the user sees and interacts with when using an application

• Web-based application: – Has a Web user interface – Runs on a server– Accessed with a computer browser


Creating a Visual Basic 2010 Windows Application

• Windows applications consist of solutions, projects, and files

• Solution: a container that stores projects and files for an entire application

• Project: a container that stores files associated with a specific portion of the solution

• A solution may contain one or more projects


Solutions, Projects, and Files (cont'd.)

Figure 1-1: Illustration of a solution, project, and file


Starting Microsoft Visual Studio 2010

Figure 1-2: How to start Visual Studio 2010 or Visual Basic 2010 Express Edition


Figure 1-3: Visual Studio 2010 Professional startup screen


Figure 1-4: Visual Basic 2010 Express startup screen

How to Create a Visual Basic 2010 Windows Application


Figure 1-5: How to create a Visual Basic 2010 Windows application

How to Create a Visual Basic 2010 Windows Application (cont’d.)


Figure 1-5: How to create a Visual Basic 2010 Windows application (cont’d.)



Figure 1-6: Options dialog box



Figure 1-7: Completed New Project dialog box in Visual Studio 2010



Figure 1-8: Completed New Project dialog box in Visual Basic 2010 Express Edition



Figure 1-9: Solution and Visual Basic Project

Managing the Windows in the IDE


Figure 1-10: How to manage the windows in the IDE

The Windows Form Designer Window

• Windows Form Designer window:– Allows you to create (design) the GUI

• Graphical user interface (GUI): – What the user sees and interacts with

• Windows Form object (or form):– Foundation for the user interface– Add other objects such as buttons/text boxes to form– Title bar with caption and Minimize, Maximize, and Close

buttons– Tab at top of designer window has Form1.vb [Design]


The Windows Form Designer Window (cont’d.)


Figure 1-11: Windows Form Designer window


The Solution Explorer Window

• Solution Explorer window:– Displays a list of projects contained in this solution– Displays the items contained in each project

Figure 1-12: Solution Explorer window


The Solution Explorer Window (cont'd.)

• Source file: a file containing program instructions

• Code: program instructions

• Form file: a file containing code associated with a Windows form

• Give each form file a meaningful name using the Properties window


The Properties Window

• Properties: a set of attributes that determine an object’s appearance and behavior

• Properties window: displays properties of selected object

• Default property values are assigned when an object is created


The Properties Window (cont'd.)

Figure 1-13: Properties window showing the Form1.vb file’s properties


The Properties Window (cont'd.)

• Properties window includes an Object box and a Properties list

• Object box:– Located immediately below Properties window title bar– Contains the name of the selected object

• Properties list:– Left column displays names of properties

• Use the Alphabetical or Categorized buttons to sort the display of properties

– Settings box: Right column containing the current value of each property

Properties of a Windows Form


Figure 1-14: Properties window showing a partial listing of the form’s properties


Properties of a Windows Form (cont'd.)

• Class definition: block of code that defines the attributes and behaviors of an object– All class definitions are contained in namespaces

• Namespace: defines a group of related classes• Dot member access operator: the period that

separates words in an object’s name to indicate a hierarchy of namespaces

• Name property: used to refer to an object in code– Give each object a meaningful name


Properties of a Windows Form (cont'd.)

• Pascal case: – First letter of each word in the name is uppercase– First part of name is object’s purpose– Second part of name is object’s class

• Text property: controls the caption displayed on form’s title bar

• StartPosition property: determines the form’s position on the screen when application starts

• Font: general shape of characters in text– Recommended font is Seqoe UI font

• Point: a measure of font sizes; one point = 1/72 inch


The Toolbox Window

• Toolbox: – Contains objects that can be added to other objects,

such as a form– Each tool has an icon and a name to identify it– Each tool represents a class from which objects, called

controls, can be created• Controls:

– Objects displayed on a form– Represented as icons in the toolbox

• Controls on a form can be selected, sized, moved, deleted, locked in place on the form and unlocked


Figure 1-15: Toolbox window

The Toolbox Window (cont'd.)


Figure 1-16: How to add a control to a form

The Toolbox Window (cont'd.)


Figure 1-17: How to manipulate the controls on a form


The Label Control

• Label control:– Displays text that user cannot edit– Used as “prompts” to explain controls or display output– Name should end with “Label”

• Control names use camel case• Camel case: lowercase first word; uppercase first

letter of each subsequent word in the name• Not necessary to assign meaningful names for labels

used as prompts because they are never used in code

• Labels used for output should have meaningful names

The Label Control (cont'd.)


Figure 1-18: Wizard application’s user interface


The Button Control

• Button control:– Performs an immediate action when clicked– Its name should end with “Button”

• Text property: specifies the text that appears on the button’s face

The Picture Box Control

• Picture box control: used to display an image on a form

• Image property: specifies the image to display

• SizeMode property: handles how the image will be displayed– Settings: Normal, StretchImage, AutoSize,

CenterImage, or Zoom


Using the Format Menu• Format menu: provides options for manipulating

controls on the form – Align option: aligns two or more controls by left,

right, top, or bottom borders– Make Same Size option: makes width and/or height

of two or more controls the same– Center in Form option: centers controls horizontally

or vertically on the form

• Multi-select controls by clicking the first, then using Ctrl-click for each additional control– First control selected is the reference control

• Its size/position is used to adjust the othersMicrosoft Visual Basic 2010: Reloaded, Fourth Edition 36

The Code Editor Window

• Events: user actions while program is running– Examples: clicking, double-clicking, scrolling

• Event procedure: set of instructions to be processed when an event occurs– Tells the object how to respond to an event

• Code editor window: used to enter event procedure’s code


The Code Editor Window (cont'd.)


Figure 1-19: How to open the Code Editor window



Figure 1-20: Code Editor window



• Class statement: used to define a class– Begins with Public Class <class name>– Ends with End Class

• Class Name list box: lists the names of objects (controls) included in the user interface

• Method Name list box: lists the events to which the selected object is capable of responding

• When you select a control from the Class Name list box and a method name, a code template for the event appears in the Code Editor window

• Syntax: rules of the language



• Keyword: a word with special meaning in a programming language

• Event code template has a procedure header and a procedure footer

• Event’s procedure header: – Begins with keywords Private Sub– Procedure name includes object name and event

name– Handles clause indicates for which objects’ events

this code will execute

• Sub procedure: block of code that performs a task



Figure 1-21: Code template for the exitButton’s Click event procedure


The Me.Close() Instruction

• Me.Close() instruction: closes the current form at run time– If the current form is the only form, the application is

terminated

• Me keyword: refers to the current form

• Method: predefined VB procedure that can be invoked (called) when needed

• Sequential processing: each line is executed in sequence– Also called a sequence structure


The Me.Close() Instruction (cont'd.)

Figure 1-22: Me.Close() instruction entered in the Click event procedure


Saving a Solution

• An asterisk appears on the designer and Code Editor tabs if a change was made since the last time the solution was saved

Figure 1-23: How to save a solution


Starting and Ending an Application

• Startup form: the form to be displayed when the application starts

Figure 1-24: How to specify the startup form

Starting and Ending an Application (cont'd.)


Figure 1-25: Project Designer window



Figure 1-26: How to start an application



Figure 1-27: Result of starting the Wizard Viewer application



• When you start a VB application, the IDE creates an executable file

• Executable file:– Can be run outside of Visual Studio 2010– Has a file extension of .exe– Stored in the project’s bin\Debug folder



Figure 1-25: How to end an application


Assigning a Value to a Property During Run Time

• Properties window is used to set property values at design time

• Assignment statement: assigns a value to a variable or property of a control– Used to set property values at run time

• String: zero or more characters enclosed in quotation marks

• Assignment operator: the = sign

• Value of the expression on the right of the = sign is assigned to the object and property on the left of the = sign


Using an Assignment Statement (cont'd.)

Figure 1-29: Assignment statements entered in the Code Editor window

Printing the Code and User Interface


Figure 1-30: How to print the code and interface during design time


Closing the Current Solution

• Closing a solution closes all projects and files in that solution– You are prompted to save any files that have

unsaved changes

Figure 1-31: How to close a solution


Opening an Existing Solution

• Only one solution can be open at any one time

• If a solution is already open, opening a different one will close the currently open solution

Figure 1-32: How to open an existing solution

Coding Errors

• Bug: an error in a program’s code

• Debugging: the process of locating and correcting bugs in a program

• Syntax error: occurs when you break one of the programming language’s rules– Most syntax errors are caused by typing errors

• Rest the mouse pointer on the mistyped instruction to see details about the error



Coding Errors (cont’d.)

Figure 1-33: Syntax error in the exitButton’s Click event procedure



Figure 1-34: Syntax error message


• Syntax errors should be corrected before starting an application

• If you start an application with a syntax error, a dialog box appears– Click No to open the Error List window


Figure 1-35: Dialog box



Figure 1-36: Result of starting an application that contains a syntax error

Programming Tutorial 1


Figure 1-54: Result of starting the Wizard application

Programming Tutorial 2


Figure 1-67: Result of clicking the Abby button

Programming Example


Figure 1-68: User interface

Summary

• Object-oriented programming language allows programmers to use objects to accomplish a goal

• Object: can be seen, touched, or used and has attributes that control its appearance and behavior

• Class: a pattern from which an object can be created

• Applications created in Visual Studio 2010 are composed of solutions, projects, and files

• Windows Form Designer window: used to create GUI applications


Summary (cont'd.)

• A form is the foundation for the user interface

• Windows Form object is instantiated from the Windows Form class

• Solution Explorer window: displays names of projects and files in the solution

• Properties window: lists an object’s properties

• All class definitions are contained in namespaces

• System.Windows.Forms namespace contains definition of the Windows Form class and class definitions for objects added to a form


Summary (cont'd.)

• Name property: used to refer to an object in code

• Text property of a form: specifies the text to be displayed in the title bar of the form and in the taskbar when running

• Form’s StartPosition property sets the position of the form when it first appears at run time

• Recommended font is Segoe UI in 9-point size

• Toolbox: contains tools for creating the GUI

• A control’s Text property value is displayed inside the control


Summary (cont'd.)

• Controls on a form can be selected, sized, moved, deleted, or locked at design time

• Label control: contains text that a user cannot edit

• Button control: performs an immediate action when clicked

• Picture box control: displays an image on a form

• Format menu provides options for aligning and sizing controls on a form

• Event procedure: the code that tells an object how to respond to an event


Summary (cont'd.)

• Use the Class Name and Method Name list boxes to select an object and event to code

• Code Editor: provides code templates for each object’s event procedures

• Me.Close() instruction: can terminate an application

• Computer automatically creates an executable file when you start a Visual Basic application in the IDE

• Use an assignment statement to assign a value to a property during run time


Summary (cont'd.)

• You should print your application’s code and its user interface

• Closing a solution closes all projects and files in it

• The process of locating and correcting errors (bugs) in a program is called debugging


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