Visual basic
- 2. Introduction Visual Basic is a tool that allows you to develop windows (graphics User Interface- GUI) application . The application have a familiar appearance to the user. Visual Basic is event-driven ,meaning code remain idle until called upon to respond to some event(button passing , menu selection,..). Visual Basic is governed by an event processor .Nothing happened 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. Event Basic code Basic code Basic code
- 3. Some features of Visual Basic • Full sets of object you draw the application. • Lots of Icons and picture for use. • Response to mouse and keyboard action. • Clipboard and printer access. • Full array of mathematical ,string handling and graphics function. • It can handle fixed and dynamic variable and control arrays. • Sequential and random access file support. • Useful debugger and error handling facilities. • Powerful database access tools. • Active X support. • Package & development wizard makes distributing your application simple.
- 4. Structure of Visual Basic Application Project (.VBP , .MAK)
- 5. Application is made of the followings terms :- • Forms :- Windows that you create for user interface. • Controls:- Graphical features drawn on forms to allows user interaction (textboxes, labels, scroll bar , command buttons etc.),(Forms and Controls are Object). • Properties :- Every characteristics of form or control is specified by a property. Ex- names , Caption size , color , position content , visual basic applies default properties . You can change it at design time or run time. • Methods :- Built in procedure that can be invoked to import some action to a particular object. • Event Procedure :- Code related to some object .This is the code that is executed when a certain event occurs. • General Procedure :- Code not related to object. This code must be invoked by the application. • Modules :- Collection of general procedures variable declaration and constant definition used by application.
- 6. Steps in Developing Applications There are 3 primary steps involved in building Visual Basic Application. 1. Draw the user interface 2. Assign properties to controls 3. Attach code to controls 1.Drawing User Interface and setting Properties: Visual Basic operates in 3 modes:- • Design Mode :- Used to build application. • Run Mode :- Used to run application. • Break Mode :- application is halted and debugger is available. Design Mode Six windows appears when you start Visual Basic. 1. Main Window :- It consist of title bar , menu bar and toolbar. The title bar indicates the project name, the current VB operating modes, and the current form. The menu bar has dropdown menus from which you control the operation of VB environment .The toolbar has buttons that provide shortcuts to some of the menus options . The main window also shows the location of current from relative to the upper left corner of the screen (measured in twips) and the width and length of the current from.
- 7. Main Window
- 8. 2.Form Window It is a central developing Visual Basic Application . It is where you draw your application.
- 9. 3.ToolBox The toolbox is the selection menu for controls used in your applications
- 10. 4. Properties Window It is used to establish initial property values for objects . The drop down box at the top of the Window lists all object in the Current form . Two views are available:- Alphabetic Categorized Under this box are available properties for the currently selected object. Press F4 of project disable from screen.
- 11. 5.Form Layout Window It shows where (upon program execution) you from will be displayed relative to your Monitor’s screen. 6.Project Window It displays a list of all forms and modules making up your application. We can also obtain a view of the form or code windows from the project window . shortcut key for project window is ctrl + r .
- 12. • As mentioned , the user interface is drawn in the form window . There are two ways to place controls on form. • 1.Double click the toolbox tools and it is created with a default size on the form you can then move it or resize it. • 2..Click the tool in the toolbox then without removing finger on mouse just drag the tools on the form window then drop the mouse ,then on the form window it shows plus sign then just draw the size of the tool whatever you want I will explain it in the next presentation with further simples examples. This presentation is helpful for the beginners .