0 Visual Basics(VB)

Visual Basics(V.B)

Introduction of V.B

V.B is stands for visual basics . It is an ideal programming language for developing professional application for microsoft window. It make use of GUI(Graphical user interface ) for creating robust (strong) and powerful application . The graphical user interface as the name suggests, uses illustration for text, which enable users to interact with an application.

                                               In a GUI environment , the number of option open to the user are much greater , allowing more freedom to the user and developer. VB 6.0 for window require at least microsoft windows95/windows nt 3.51 , 486 processor and a minimum of 16 mb of ram . A complete installation of the most powerful version of visual basics 6.0 , the enterprise edition, requires more than 250 mb of hard disk space.

Features of visual basics

• It can easier to comprehend thing in a quicker and easier way.
• It makes such as easier comprehension , allowing more freedom to the user and developer.
• It such as easier comprehension, user friendliness, faster application development.
• If they aspects such as introduction to active x technology and internet.
• It make vb in intesting tool to wark with.

Integrated Development environment (IDE)

It is term commonly used in the programming world to describe the interface and environment that you can  use to create our application. It is called integrated because we can access virtually all of the development tools that we need from one screen called an interface . The ide is also commonly referred to as the design environment or program. 

The V.B IDE is made up of a number of component:

• Menu bar
• Tool bar
•  Project explorer
• Properties windows
• Form layout window
• Tool box
• Form designer
• Object browser

1. Menu bar => It can displays the command that are required to build an application  .The main menu item that can be chosen when needed.

Tool bar button                    _                                   menu equivalent
Adds a new form Adds a new module Opens an existing  windows Saves the current project Lock and unlock the command control Display the properties windows Display the object browser	Add form command on the project menu. Add module command on the project menu. Open project on the file menu. Save project on the file menu. Lock control on the form format menu. Properties window on the view menu. Object browser on the view menu.

2 . Tool bars => It is contain a set of control that are used to place on a form at design time thereby creating the user interface area . Additional controls can be included the tool box by using componenet menu item on the project menu. 

3. Project explorer => The windows titled project in the project explorer , which display the components of the project. The project componenet are  organised in folders , & the project windows is called project exployerer because it has the look of the window exployerer.
4.Tool Box 

• Pointer = The pointer helps to move and resize the controls and forms.
• Label => The label displays a text that the user cannot modify or interact with.
• Frame => Frame control serves as a visual and functional container for controls.
• Checkbox => It can displays a true /false or yes / no option.
• Text box => It is a control used to display message and enter text.
• List box => It can displays a list of items from which a user can select one.
• Combo box => It can contain a text box and a list box . This allow the user to select an item from the dropdown list box.
• Hscroll bar and Vscroll bar => It can allow the user to select a value within the specified range of values .
• Timer controls =>It can executes their events at specified intervals of time.
• Dir list box=> It allows the user to select directories and paths , which are displayed.
• Shape controls => It adds a shape (rectangle , circle,) to form.
• Image => It controls is used to displays icons , bitmaps, metafiles etc.
• Ole => It controls is used to link an objects and mainpulate data from other windows based application.
• Picture box => The displays icons and metafiles . It can displays text or acts as a visual container for other controls.
• Command button=> It carries out the specified action when the user choose it.
• Option button => It controls which is a part of an option group allow the user to select one option even if it displays multiple choices.
• Driver list box=> It displays the valid drives and allow the user to select one of them.
• File list box=> It displays a set of file from which a user can select the desired one.
• Line controls=> It can controls a straight line to the form.
• Data controls=> It enables the user to connect to an existing databases and displays information.

Object Browser=>The object browser allow us to browse through the various properties , events and method that are made available to us. It is accessed by selecting object browser from the view menu or by pressing key f2.

A property is represented by a small icons that has a hand holding a piece of paper . Method are denoted by little green block , while events are denoted by the yellow lighting bolt icon.

Properties 

A few common properties of vb are as follows:

• Name = The property set the name of the control, through which you can access the controls properties and methods. 
• Appearance = This property can be 0 for a look or 1 for a 3d look . The example in this book  use the 3d look for most controls.
• Back color = This property sets the background color on which text is displayed or graphic are down.
• Fore color= This property sets the forecolor (pen color or text).
• Font =  This property sets the face, attributes and size of the font used for the text on the controls.
• Caption = This property sets the text that is displayed on many controls that does not accept input . example the text on label controls, caption on command.
• Text = This property sets the text that is displayed on the control that accept user input. example Box controls.
• Width height = This property set the controls dimension.
• Left top= These properties set the coordinates of the controls upper _ left corner, expressed in the unit of the container(usually a form).
• Enabled = by default , this property value is true , that means the controls can get the focus.
• Visible = Set the property false to make a controls invisible.

A few common events for visual basics

• Mouse events= The events small by mouse action are the most common events in programming with visual basics. Most of the element of the user interface can be manipulation with the mouse and programming mouse events in your number one job as a vb programmer.

1. Mouse down, mouse up = The mouse down events takes place when the mouse button is pressed , and the mouse up events take place as it is released.
2. Click, dbl Click = The click events take place when the user click the left mouse button , the dbl click events takes place when the user dbl click the left mouse button.
3. Mouse move= The events takes place continuously as the mouse is moved over a controls. 

Data types variables

visual basics recognizes the following six types of variables:

• Numeric
•  String
• Boolean
• Date
• Object
• Variant

The two major variables types are numeric and string. Numeric variables store number and string variable store text. varient variable can store any type of data.

• Numeric variables = All programming laguage provides a variety of numeric data types , including the following:

1. Integers 
2. Single or floating point no with limited.
3. Double , or floating point no with extreme.

• Integers = It ca stores integer value in the range 32768 to 32767.
• Long = It ca stores long integer in the range 2147483648 to 2147483647.
• Single= It can stores single precision floating point number. It can represent negative number in the range - 3.402823 E 38 to 1.401298 E 45. The value 0 cannot be represent precisely.
• Double = It can stores double precision floating number . It can represent negative number in the range -1.79769313486232E308 to -4.9406564841247 E 324 & positive number in the range 4.940656458412 E -324 to 1.79769313486232E308.
• Currency = It can stores fixed point number with four decimal digits. The currency data types ca represent number in the range -922337203685477.5808 to 922337203685477.5807. 

Working with forms