VB

Chapter-1 Introduction to Visual Basic GUIA GUI is a graphical (rather than purely textual) user interface to a computer. The term came into existence because the first interactive user interfaces to computers were not graphical; they were text-and-keyboard oriented and usually consisted of commands you had to remember. The command interface of the DOS operating system (which you can still get to from your Windows operating system) is an example of the typical usercomputer interface (character/command user interface-CUI) before GUIs arrived. An intermediate step in user interfaces between the command line interface and the GUI was the non-graphical menu-based interface, which let you interact by using a mouse rather than by having to type in keyboard commands. Today's major operating systems provide a graphical user interface. Applications typically use the elements of the GUI that come with the operating system and add their own graphical user interface elements and ideas.

Programming languagesThere are various types of programming languages, each was developed to solve a particular kind of problems. 1. Procedural languagesA computer programming language that follows, in order, a set of commands. Examples of computer procedural languages are BASIC, C, FORTRAN, and Pascal. 2. Object Oriented programming languageA type of programming in which programmers define not only the data type of a data structure, but also the types of operations (functions) that can be applied to the data structure. In this way, the data structure becomes an object that includes both data and functions. In addition, programmers can create relationships between one object and another. For example, objects can inherit characteristics from other objects.

3. Event Driven programming languageIn computer programming, event-driven programming also known as event-based programming is a programming method in which the flow of the program is determined by user actions such as mouse clicks, key presses.

VB EnvironmentVB is event-driven programming language, which has some of the features of object oriented programming language. In VB you will work with objects, which has properties and methods. ObjectsObject is an element from a VB program, such as a control, form or code module that holds programming statement. PropertiesA Property helps to differentiate a control from other control because the property shows appearance and behavior of a control. Properties have values such as colors, names, size and location on the form. MethodsActions associated with the objects are called methods. Some common methods are move, print, show etc. EventEach action by the user causes an event, Event is an activity that occurs during program execution, such as mouse click, key-press, activate etc.

VB EnvironmentAn integrated development environment (IDE) is a programming environment that has been packaged as an application program, typically consisting of a code editor, a compiler, a debugger, and a graphical user interface (GUI) builder. Main Window- Title bar, Menu bar & tool bar Tool Box Form Window Project Explorer Properties window Form Layout window

Visual Basic Projects-

The Project file with extension .vbp Each form in project saved with extension .frm Optionally you can have .bas files that contains basic statement accessed from any form of the project. (These files are also called standard code module) If you include additional controls which are not part of standard control set then the .ocx file names will be included in your project. After you save a project, VB automatically adds one or more files to your project with extension .vbw(VB project workplace). This file holds information about each of your projects form.

Errors in VB1. Compile time errors- (Occurs when you press enter key or when you execute code) Project code->m/c code=>Compile time errors if you break syntax rule Ex. if a