VISUAL BASIC BY MALIK TABLE OF CONTENTS Visual Programming:- Low level and High level Procedure Oriented and Event Oriented Low visual and high visual Language Interoperated and complied Language History of Visual Basic Visual Basic IDE Student Exe Project Visual Components of Visual Basic IDE Tool Box Manu Bar Icon Toolbar Features of Objects Objects Properties Some Common Object Properties Object Methods Object Events Events Triggered by the Mouse Events Triggered by the Keyboard Event Procedure Changing Object Properties at Run Time Adding comments Concepts of Focus Exercises Visual Basic Project Naming a project Saving a project Running a project Complied applications Compile to P-Code Compile Native Code Making Executable File Debugging Correcting System Errors Correcting Run Time Errors Correcting Logic Errors Be bugging Object Exercises Working with Forms Basic component of Forms Changing Forms Properties Formatting Control on Forms Form Events Form Methods Adding Manu to Form Multiple Form Visual Basic Applications Accessing Information on Form Visual Basic Multiple Documents Interface(MDI) Exercises Visual Basic Programming Data and Data Types Variables Type of Variables String type Variables Numeric Type Variables Special Variables Scope of Variables Lifetime of Variables Constants Assignments Statement Expressions Arithmetic Expressions Hierarchy of Operations Relation Expressions Logical Expressions Order of Procedure of Operation Built-in Factions Basic Input/Output Input and Output Boxes Message Box Modality of Message Box Input Dialog Box Exercises Control Statements Go to Statement Conditional Control Statement Selection Structure If …….. then structure If …..then…..else Structure Select Case Structure Loop Structure While ……..wend Structure Do …… while loop Structure Do …….Un till loop Do……..loop while Do……..loop until For……..next Loop Exit for and Exit Do Structure Exercises Basic ActiveX Controls Command Button Label Control The Timer Text Box Check Boxes Option Buttons Frames List Box Control Combo Box Control Scroll Box Control File Controls Exercises Arrays One Dimensional Arrays Declaring Arrays Assigning Value to An Array Two Dimensional Array Entering Data to Two Dimensional Array Control Arrays Exercises Graphics Drawing With Visual Basic Scale Properties Types of Graphics Using Colors Graphics Controls Image Box Control Picture Box Control Shape Control Graphics Methods Line Method Circle Method Pest Method Cls Method Move Method Exercises Advance ActiveX Controls Adding Advanced Controls to Toolbox The common Dialog Control Common Properties of Dialog Boxes Open Dialog Box Save As Dialog Box Color Dialog Box Font Dialog Box Print Dialog Box Rich text Box Control Msflexgrid Control Exercises Procedure and Functions Subprograms Types of Subprograms Scope of Subprograms Writing Subprograms in From Modules Sub Procedures Functions Argument Passing Mechanism Creating a Separate Code Module Exercises Database Programming Database Relational Databases Biblio.mbd Database Management System (DBMS Visual Data Manager Entering Data Into the database Data Management Tools Data Control Data Bond Controls Record set Object Data Access Object (DAO) Accessing DAO Objects Naming DAO Objects Refereeing To DAO Object Object Variables Workspace Collection Databases Collection Table Defs Collection Fields Collection Indexes Collection Seek Method Structured Query Language(SQL) Exercises ActiveX Data Objects ActiveX Data Object(ADO) The ADO Data Control Data Bound Controls ADO Object ADO Collection Connection Object Command Object Record set Object Data Environment Designer Accessing Records By Creating Command Object Using Data Environment with the Data Grid Control Data Report Designer Data Report Object Exercises Visual Basic and Web The Web sever Control Web browser Events The Internet Explorer Object Exercises Scripting Objects Visual Basic Scripting Objects File System Objects (FSO) Objects Text Stream Object Reading Data From Text Files Managing Folders And Files Exercises Introduction To Visual Basic Computer Programming Language The computer languages can be categorized based upon the following criteria: Low level and High level Procedural and Event oriented High visual and low visual Interpreted and Complied Low-level & High-level A computer language can be described as a low-level or high-level language. A language close to the machine language is called low-level language and a language close to human-language is called high-level language. Low-level lingual are to the machine language. The machine language consists of 0s and 1s. The program written in machine language work with great speed. Assembly language is an example of low-level language. It is generally used for writing operating system and firmware. High-level languages are people-oriented. The instructions in these languages are more like human languages. BASIC, FORTRAN, COBOL, PASCAL, etc are examples of high-level languages. Unlike low-level languages, these languages are easier to learn. These languages are used for writing application programs. A high-level language, for example may be used for writing a program for maintaining the budget of a company. Procedure-Oriented And Event-oriented The program written in procedure –oriented language is executed with out any action by the user. A computer program written in a procedure- oriented language is executed, statement by statement until all the code is executed. Procedural languages are high-level languages. Prior to 1990, most high-level languages were procedural languages. Program written in event-oriented languages are different as their execution depends upon the user. They wait for the user to take some action and they perform a task in response to the action of the user. Event-oriented languages were developed with the advent of Microsoft Windows for MS-DOS computer systems. These systems provided Graphical User Interface or GUI (pronounced as goo-ey) In the GUI, an event may be the pressing of a key on the keyboard or the click of a mouse button. In an event-oriented program, the computer waits for an event and it takes the action accordingly. Low-Visual and High-Visual Languages Computer languages can also be described as low-Visual and High- Visual languages. In low-visual language it is often difficult to design computer forms and reports. High-visual languages, on the other hand, support GUI. Theses languages provide easy methods for designing, forms, reports, data entry screens, etc. Visual Basic language is an example of high-visual language. Interpreted and Complied Languages A computer language can be interpreted or complied. In interpreted languages, the programs executed statement by statement by interpreting each statement of the program. In complied languages, the whole program is first complied into machine code and then it is executed. Visual Basic is both interpreted and complied language. When the visual Basic program is developed , it is executed in interpreted mode. After completing the program, it is complied and the complied and the complied program are used. History of The Visual Basic Visual Basic evolved from BASIC (Beginner’s All-purpose Symbolic Instruction Code). BASIC was developed in the 1960s by Professors John Kemmeny and Thmoas Krrtz of Dartmooth College. It was developed as a language for writing simple programs to help people learn how to program. BASIC became a popular language and its widespread use led to many enhancements in the language. With the development of Graphical User Interface for personal computer (Microsoft Windows) in the late 1980s and early 1990s, the version of BASIC suitable for GUI environment was developed. It was named Visual Basic and it was developed by Microsoft Corporation in 1991. Prior or Visual BASIC, writing Windows-based application was very difficult and time-consuming, Visual BASIC greatly simplified writing of window application programs, since 1991, eight versions of Visual Basic have been released. The latest version is Visual Basic Net. Visual Basic is a Microsoft Windows programming language. It provides and Integrated Development Environment (IDE) for creating applications, the environment is which a programmer can create, run and debug a program is called IDE. The processes of rapidly writing an applications program is sometimes also called Rapid Application Development (RAD). Visual Basic is the worlds, most widely used RAD. There are three different versions of Visual Basic. These are: the learning Edition, Professional Edition and Enterprise Edition. Each edition provides specific features and is suitable for a specific se of environment. Visual Basic Learning Edition The learning Edition provides basic programming features. This edition is generally used by students in educational institutions for learning the language. Visual Basic Professional Edition Professional Edition provides full features of the language. It is used by professional programmers to develop Visual Basic application programs for commercial purpose. Visual Basic Enterprise Edition Enterprise Edition provides features for creating a distributed application program. This edition includes all the features of the Professional Edition, plus tools such as SQL Server, IIS, SNA server, etc Visual Basic IDE Visual Basic is a both a tool and a language. The tool is the Visual Basic Integrated Development Environment (IED). It provides facilities for writing, debugging and running programs in one environment. It is used to develop the Graphic User Interface ((GUI) of the program, the language is used to write the code that executes behind the GUI of the program. Steps in Developing VB Application An application in Visual Basic development environment is developed in three steps. These steps are followed in every application whether it is a simple or a complicated and extensive application. These steps are: Drawing the user interface by placing controls on the form. Assigning properties to the controls. Writing and attaching the code to the control events and writing independent procedures. The Visual Basic application is developed in stages. In each stage, the code for one procedure is written and tested. This makes writing of the application programs simpler. It also minimizes program errors. Standard EXE Project When Visual Basic is loaded, the new project dialog window is displayed. This dialog window contains various types of applications that can be created in Visual Basic IDE. It contains the following three tabs. The New tab contains options for creating new Visual Basic applications. The Existing tab is used for opening an existing application saved on the disk. The Recent tab is used for opening a project that has been recently used onto the Visual Basic IDE. The New Project dialog is displays each time the Visual Basic is loaded, their is check Box on the lower left corner of this dialog. If this check box is checked, this dialog is not displayed when the Visual Basic is started. It is, however, displayed when the New Project command in the File menu is executed. The New Project dialog window contains a number of different types of applications that can be created in Visual Basic. Their number and type on this dialog window depends upon the edition of the Visual Basic. For example, the learning edition of visual basic contains fewer items that the Professional Edition, the above figure shows the new project dialog of visual basic Enterprise Edition. In New Project dialog, Standard Exe is highlighted by default, it is used to create a standard executable program in Visual Basic, and standard EXE application uses the most common Visual Basic features. Visual Components of Visual Basic IDE Figure below show the visual basic IDE for Standard EXE project. The visual basic IDE consists of various components and the following windows: Form Window Form Layout Window Properties Window Project Explorer Window Toolbox Title Bar Menu Bar Tool Bar Tool Box Form Form Window Form window contains a form. The graphical user interface (GUI) of the visual basic program is created and displayed on this window. The FUI of a program consists of several buttons, text boxes, etc/ the user provides input through various controls on the form and the output of the program is also displayed on the form. Form Layout Window Form Layout a window is used to specify the position of the program window on the computer screen when the program is executed. It consists of an image representing the computer serene and a form. The position of the active form relative to the computer screen is shown. The position of the form on the screen can be adjusted by dragging the form with the mouse the desired position. Properties Window The properties of an object in visual basic its attributes such as size, color, position, appearance, font, etc. Properties window displays these attributes of the selected object. Each control in visual basic has a unique set of properties. Some properties such as height, width, color etc, are common to all controls. While other properties are unique to each object. When an object or a control is selected. Its respective properties appear in the properties window. Properties window contains two tabs: alphabetic and Categorized. When alphabetic tab is selected, the properties are listed in alphabetic order. This is the default setting.