Unit-2: Visual programming lecture notes (Visual Basic Programming)

Unit-2: Visual programming lecture notes (Visual Basic Programming) in Visual programming uploaded at P.R.Engineering college

Unit-2: Visual programming lecture notes (Visual Basic Programming) in Visual programming at P.R.Engineering college uploaded by P.R.Engineering college Staff in lecturenotes.net

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INTRODUCTION

This unit about programming in Visual Basic which is a high level programming language evolved from the earlier DOS version called BASIC. BASIC means Beginners’ All-purpose Symbolic Instruction Code. It is a very easy programming language to learn. Now, there are many versions of VB exist in the market, the most popular one and still widely used by many VB programmers is none other than Visual Basic 6. Most recently we have VB.net, VB2005, VB2008 and the latest VB2010. Both Vb2008 and VB2010 are fully object oriented programming (OOP) language.

Microsoft Visual Basic development system version 6.0 is the most productive tool for creating high-performance components and applications. Visual Basic 6.0 offers developers the ability to create robust applications that reside on the client or server, or operate in a distributed n-tier environment. Visual Basic 6.0 is the Rapid Application Development (RAD) tool available either as a stand-alone product or as a part of the Visual Studio 6.0 suite of tools.

LEARNING OBJECTIVES

• Understand the benefits of using Microsoft Visual Basic 6.0 for Windows as an application tool
• Understand the Visual Basic event-driven programming concepts, terminology, and available tools
• Learn the fundamentals of designing and implementing a Visual Basic application
• Learn to use the Visual Basic toolbox
• Use the menu design window
• Get a basic understanding of database access and management using databound controls

THE INTEGRATED DEVELOPMENT ENVIRONMENT

Visual Basic is a tool that allows you to develop Windows (Graphic User Interface - GUI) applications. The applications have a familiar appearance to the user.
 Visual Basic is event-driven, meaning code remains idle until called upon to respond to some event (button pressing, menu selection, etc.). Visual Basic is governed by an event processor. Nothing happens until an event is detected. Once an event is detected, the code corresponding to that event (event procedure) is executed. Program control is then returned to the event processor.

Some Features of Visual Basic are:

1. Full set of objects
2. Response to mouse and keyboard actions
3. Full array of mathematical, string handling, and graphics functions
4. Can handle fixed and dynamic variable and control arrays
5. Sequential and random access file support
6. Useful debugger and error-handling facilities
7. Powerful database access tools
8. ActiveX support
9. Package & Deployment Wizard makes distributing your applications simple

Visual Basic comes with its Integrated Development Environment (IDE). The IDE gives you everything you need to create great applications, to write code for them, to test and fine-tune them, and, finally, to produce executable files.

Running the IDE

You can choose from several ways to launch the Visual Basic IDE, as is true for any Windows executable:
You can run the Visual Basic 6 environment from the Start Menu (as given in Figure 2.1); the exact path to the menu command depends on whether you have installed Visual Basic as part of the Microsoft Visual Studio suite.
 
Figure 2.1 Selecting Microsoft Visual Basic 6.0 from Start
 
• You can create a shortcut to the IDE on your desktop and run it by simply double- clicking on it.
• When Visual Basic is installed, it registers the .vbp, .frm, .bas, and a few other extensions with the operating system. Therefore, you can run the environment by double-clicking on any Visual Basic file.
• If you have installed Microsoft Active Desktop, you can create a shortcut to the Visual Basic IDE on the system taskbar. This is probably the fastest way to run the IDE: it’s similar to a desktop shortcut, but you don’t have to minimize other windows to uncover it.

Selecting the Project Type

The first time you run the Visual Basic IDE, you’re asked to select the type of project you want to create, as you can see in Figure 2.2.

Some of the project types that Visual Basic supports are:
• Standard Windows EXE programs
• ActiveX EXE files
• ActiveX DLLs
• ActiveX controls
• Programs written by the Visual BasicApplication Wizard
• Data projects
• IIS (the Microsoft Internet Information Server) applications
• Visual Basic add-ins
• ActiveX document DLLs
• ActiveX document EXE files
• DHTML applications
• VB Enterprise Edition controls
 
Figure 2.2 Types of projects in VB6.0
 
This list of project types indicates some of the ways Visual Basic has grown over the years. Select Standard EXE from the new project dialog (as in Figure 2.2) and what you’ll be confronted with is shown in Figure 2.3, which is the main programming environment. You do all your form design and coding from this window. The main programming environment has the following windows:

Form Design Window

This is where you design your form. A form is what you will present to a user of your application. A form could be an introduction screen, it could be a dialog box giving the user options, and it could be a box containing a warning. All of your VB programs will revolve around a number of forms.

The form window - When you start Visual Basic, a default form (Form1) with a standard grid (a window as shown in figure 2.4, consisting of regularly spaced dots) appears in a pane called the Form window. You can use the Form window grid to create the user interface and to line up interface elements.
 
Figure 2.3 The Visual Basic 6 environment
 
Figure 2.4 Form Window
The Toolbar provides quick access to commonly used commands. These will be explained later in the document.

The Toolbox (Control Bar) is a floating window (Figure 2.5) which provides the tools for designing/creating an application on your form. They can create buttons, text boxes, labels, scroll bars and other commonly used windows items.

To build the interface elements, you click an interface control in the Visual Basic toolbox, and then you draw the user interface element on your form by using the mouse. This process is usually a simple matter of clicking to position one corner of the element and then dragging to create a rectangle the size you want. After you create the element — say, a text box — you can refine it by setting properties for the element. In a text box, for example, you can set properties to make the text boldface, italic, or underlined.
 
Figure 2.5 Tool Box (Control Bar)   Figure 2.6 Property Window
 
The Property Window - With the Properties window (figure 2.6), you change the characteristics (property settings) of the user interface elements on a form. A property setting is a characteristic of a user interface object. For example, you can change the text displayed by a text box control to a different font, point size, or alignment.

The Project Window (figure 2.7) includes all the forms, programming code and other files needed and provides access to them with two special buttons: View Code and View Object.
 
Figure 2.7 Project Window

To display the Project window, click the Project Explorer button on the Visual Basic toolbar. If the window is currently docked, you can enlarge it by double-clicking the title bar. To re-dock the Project window, double-click its title bar again.

The project file maintains a list of all the supporting files in a Visual Basic programming project. You can recognize project files by their .vbp file name extension. You can add individual files to and remove them from a project by using commands on the Project menu. The changes that you make will be reflected in the Project window.

If you load additional projects into Visual Basic with the File menu Add Project command, outlining symbols appear in the Project window to help you organize and switch between projects.

STEPS FOR BUILDINGA VISUAL BASIC APPLICATION

After designing the application, for building an application in Visual Basic following steps are to be taken:

Draw the Interface  - Create the form and the various objects on the
form using toolbox.
Set the Properties  - Set the properties of the various objects on the
form with the help of properties window.
Write the events code - In the code window, write the code associated
with each object on the form and then run the application.

Title:
Unit-2: Visual programming lecture notes (Visual Basic Programming)

Subject:
Visual programming

Institute:
P.R.Engineering college

Unit-2: Visual programming lecture notes (Visual Basic Programming)

Unit-2: Visual programming lecture notes (Visual Basic Programming) in Visual programming uploaded at P.R.Engineering college

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