Glossary

A
abstract class: (1) A class with at least one pure virtual function that is used as a base class for other classes. The abstract class represents a concept; classes derived from it represent implementations of the concept. You cannot construct an object of an abstract class. See reference class. Contrast with concrete class. (2) A class that allows polymorphism.
abstract data type: A mathematical model that includes a structure for storing data and operations that can be performed on that data. Common abstract data types include sets, trees, and heaps.
access: An attribute that determines whether or not a class member is accessible in an expression or declaration. It can be public, protected, or private.
access declaration: A declaration used to adjust access to members of a base class.
access function: A function that returns information about the elements of an object.
access resolution: The process by which the accessibility of a particular class member is determined.
access specifier: One of these three C++ keywords: public, private, or protected.
action: The initiation of an alteration performed by a tool or function.
active time: See lifetime of an object.
address: A name, label, or number identifying a location in storage, a device in a system or network, or any other data source.
address space: (1) The range of addresses available to a computer program. ANSI. (2) The complete range of addresses that are available to a programmer. (3) The area of virtual storage available for a particular job. (4) In the AIX operating system, the code, stack, and data that can be accessed by a process. IBM.
aggregate: (1) An array or a structure. (2) A compile-time option to show the layout of a structure or union in the listing. (3) An array or a class object with no private or protected members, no constructors, no base classes, and no virtual functions. (4) In programming languages, a structured collection of data items that form a data type. I.
AIX operating system: IBM's implementation of the UNIX operating system. The RISC System/6000 system, among others, runs the AIX operating system. See UNIX operating system.
alignment: (1) The storing of data in relation to certain machine-dependent boundaries. IBM. (2) The positioning of data elements on 1-, 2-, 4-, 8- or 16-byte boundaries according to the data type and active packing method. See boundary alignment.
ambiguous derivation: A derivation where the class is derived from two or more base classes that have members with the same name.
American National Standard Code for Information Interchange (ASCII): The standard code, using a coded character set consisting of 7-bit coded characters (8 bits including parity check), that is used for information interchange among data processing systems, data communication systems, and associated equipment. The ASCII set consists of control characters and graphic characters. Note: IBM has defined an extension to ASCII code (characters 128-255).
American National Standards Institute (ANSI): An organization consisting of producers, consumers, and general interest groups, that establishes the procedures by which accredited organizations create and maintain voluntary industry standards in the United States. ANSI.
animate: Make or design in such a way as to create movement.
animation rate: The number of thousandths of a second that pass before the next bitmap is displayed for a button while it is animated.
anonymous union: A union that is declared within a structure or class and that does not have a name.
ANSI: American National Standards Institute.
application: (1) The use to which an information processing system is put; for example, a payroll application, an airline reservation application, a network application. IBM. (2) A collection of software components used to perform specific types of user-oriented work on a computer. IBM.
argument: A parameter passed between a calling program and a called program. See default argument.
arithmetic object: In the AIX operating system, an integral object or objects having the float, double, or long double type. IBM.
arithmetic underflow: See underflow.
array: An aggregate that consists of data objects, with identical attributes, each of which may be uniquely referenced by subscripting.
array declarator: The part of a statement that describes an array. The description includes the name of the array, the number of dimensions, and the size of each dimension.
array element: (1) A data element in an array. (2) An object that is identified and accessed with an array name and index. A contiguous set of such objects that have the same type make up the contents of an array.
array implementation: In the Collection Class Library, implementation of an abstract data type using an array. Also called a tabular implementation.
ASCII: American National Standard Code for Information Interchange
assembler language: A source language that includes symbolic machine language statements in which there is a one-to-one correspondence with the instruction formats and data formats of the computer. IBM.
asynchronous: (1) Pertaining to two or more processes that do not depend on the occurrence of specific events such as common timing signals. T. (2) Without regular time relationship; unexpected or unpredictable with respect to the execution of program instructions. IBM. Contrast with synchronous.
attribute: A named property of an entity. IBM.
audio attribute: A property pertaining to recorded information that can be heard. The standard audio attributes are mute, volume, balance, treble, and bass.
audio format: The way the audio information is stored and interpreted.
audio track: (1) The audio (sound) portion of a program. (2) The physical location where the audio is placed beside the image. (A system with two audio tracks can have either stereo sound or two independent audio tracks.) Synonym for sound track.
automatic data: See transient data.
automatic storage: Storage that is allocated on entry to a routine or block and is freed on the subsequent return. Sometimes referred to as stack storage or dynamic storage.
automatic storage management: The process that automatically allocates and deallocates objects in order to use memory efficiently.
auto-reset event: In the Windows operating system, an event used to signal a single thread that an application has completed. See event.
auxiliary classes: Classes that support other classes. Auxiliary classes in the Collection Class Library include classes for cursors, pointers, and iterators.