CMPnet''''s TechEncyclopedia CNET''''s glossary MSDN Online Library''''s glossary

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Abs Function: Returns the absolute value of a number. The absolute value of a number is its unsigned magnitude. For example, Abs(3) and Abs(-3) both return 3.

Abstraction: According to this object-oriented principle, an operation''''s complex details should be hidden from the user, and only an object''''s functionality is exposed to other objects. In database access, the client-side programmer never has direct access to the database. Instead, data is accessed by the front end through objects, which then communicate with the database.

Activate Event: Associated with a form and is fired when that form becomes the active window.

Active Server Pages (ASP): Web pages containing scripting code, developed by Microsoft starting with version 3.0 of Internet Information Server (IIS). The server-side execution environment executes the scripts or components on a server.

ActiveX: Technologies based on COM and DCOM, which enable software components written in different languages to work together over a network. See also: ActiveX Control, Component Object Model, Distributed Component Object Model.

ActiveX Control: A software module based on COM. ActiveX controls add user interface functions, and work by calling components that blend in with the program. You can embed them in Web pages or use them to create client/server applications that run over a network. See also: Component Object Model.

ActiveX Data Objects (ADO): Microsoft''''s data access programming interface. ADO is an object-based interface that works at the application level to provide data access to Visual Basic applications or any applications that support COM. Applications use this interface to retrieve and update data from a database or other data store. See also: Component Object Model, OLE Database.

ANSI (American National Standards Institute): ANSI-standard programming languages conform to ANSI recommendations. These standards are designed to eliminate variations that could cause problems in transporting programs from one type of computer system to another.

Application Programming Interface (API): An interface consisting of functions, messages, data structures, data types, and statements used by a programming language to access another programming language or program. For example, the Win32 API allows Visual Basic programmers to access functions in the Windows operating system.

Argument: A value that is passed to a subroutine, function, or method that affects the way a task is performed. Also called a parameter.

Array: A group of data elements with the same name and data type. Arrays can be multidimensional—for example, containing rows and columns. Each element in an array is distinguished by its unique location, also called an index. In Visual Basic, you can have a control array that consists of a group of form controls of the same type with the same name.

Asc Function: Returns a numeric value that is the ASCII code for the first character in a string expression.

ASCII (American Standard Code for Information Interchange): A coding scheme that assigns numeric values to letters, numbers, punctuation marks, and certain other characters on a keyboard.

Asynchronous: Refers to events that are not coordinated in a linear manner, such as storing and forwarding messages, or starting a new operation before completing the current one. A program sends an asynchronous query to the database and continues processing. See also: Synchronous.

Atn Function: Returns the arctangent, in radians, of n.

Back End: The database or data store that provides data to the frontend application.

Binary Large Object (BLOB): A database field holding digitized information such as text and images.

BOF Property: Returns a value that indicates whether the current record position is before the first record in a recordset. See also: EOF Property.

Bound Control: A control, usually on a form, you can link to a data source, such as a data control or recordset, and use to display that data. Textboxes, checkboxes, image controls, labels, and picture boxes are all bound controls.

CCur Function: Converts any valid expression to the Currency data type.

CDbl Function: Converts any valid expression to the Double data type.

Change Event: Indicates the contents of a control have changed. Depending on the type of control, this event occurs in response to various actions. For example, when the text in a textbox changes, its Change event fires.

Choose Function: Selects and returns a value from a list of arguments based on the index you provide to the function.

Chr Function: Returns a one-character ASCII code for an ANSI character code. For example, Chr(65) returns "A".

CInt Event: Converts any valid expression to the Integer data type.

Class Module: A template used in Visual Basic to create your own objects. Class modules can include code for methods, properties, and events. Class modules have no visible user interface.

Class: The basic unit that defines an object. A class contains properties and methods that expose its characteristics and functionality to other classes.

Click Event: Occurs when the user presses and releases a mouse button over an object. Might also occur when the value of a control changes.

Client: A workstation or personal computer that accesses information on remote servers, then presents and manages the information retrieved from the server. See also: Client/Server, Fat Client, Server, Thin Client.

Client/Server: A two-tier computing model in which the client (a workstation or PC) requests information from the server, and the server supplies the information needed. In this type of architecture, the client typically contains all the programming logic. A local area network (LAN) or wide area network (WAN) connects both client and server.

CLng Event: Converts any valid expression to the Long data type.

Combo Box: A Visual Basic control that combines the features of a textbox and a listbox. Users can type in the textbox portion or select an item from the list portion of the control.

Collection: An object that stores an ordered set of items as a single unit. The items in a collection can be of varying data types (even other objects), and are related only by the fact that they are stored in the collection.

Command Function: Returns the argument portion of the command line that launches VB.

Common Object Request Broker Architecture (CORBA): An Object Management Group standard for communicating between distributed objects. With CORBA, programs written in any language can execute from anywhere on a network and from any platform.

Compiler: Translates code into an executable file.

Component Object Model (COM): Microsoft''''s infrastructure for code modules that are independent of programming languages and computer platforms. The COM specification allows objects to expose interfaces that can be used by any programming language that supports the creation of COM objects. ActiveX technologies are based on COM. See also: Distributed Component Object Model.

Component: A routine or module that is ready to use with other components or programs within a larger system. See also: Component Object Model.

Concurrency: A term used when referring to data access and two users are updating the same record at the same time. This is an issue that must be handled by the programmer.

Constant: A variable that stores a value that remains constant throughout the program.

Control: A tool for creating objects on a VB form. Most controls are used to create user interface elements, such as command buttons, image boxes, and listboxes. Also: A module that enhances a program''''s functionality, such as an ActiveX control.

Cos Function: Returns the cosine of the angle n. The angle n is expressed in radians.

CreateObject Function: Creates an OLE Automation (ActiveX) object of whatever type you specify.

CSng Function: Converts any valid expression to the Single data type.

CStr Function: Converts any valid expression to the String data type.

CurDir Function: Returns the current path for the specified drive.

Custom Control: A reusable component that provides a discrete piece of functionality you do not have to code from scratch.

CVar Function: Converts any valid expression to the Variant data type.

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Data Access: How Visual Basic communicates with a database or data store to retrieve, update, add, and delete data.

Data Access Objects (DAO): A COM-based, Microsoft programming interface used for data access. DAO uses the Jet database engine for data management, and uses Open Database Connectivity Direct (ODBCDirect) to provide access to ODBC databases. See also: Component Object Model, Open Database Connectivity, Remote Data Obj

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