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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; that is, it cannot be instantiated. 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. The preferred (or ISO or standard) way to modify access is a using declaration.
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
(1) The initiation of an alteration performed by a tool or function. See event, public, member function. (2) In visual programming, a specification of a function that a part can perform. VisualAge uses the specifications to generate connections between parts. Actions are resolved to member function calls in the generated code. All actions are members of a part's class; however, not all public member functions are actions.
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 class, struct, or union with no user-declared constructors, no private of protected non-static data members, no base classes, and no virtual functions. (2) A compile-time option to show the layout of a structure or union in the listing. (3) An array or a class, union or struct with no user-declared constructors, no private or protected non-static data members, 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.
alias
(1) An alternative label. A label and one or more aliases may be used to refer to the same data element in a computer program. (2) In the C++ language, an alternative name for a namespace. See namespace. (3) In VisualAge C++, an option that determines which alias assertions are to be applied during optimization. (4) In the AIX operating system, an alternative name used for a network.
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. (3) On a graphical user interface, bringing an object into line with one or more reference points.
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
An unnamed object whose type is an unnamed union.
ANSI
American National Standards Institute.
API
Application programming interface.
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.
application programming interface (API)
A language and message format used by an application program to communicate with another program that provides services to it.
argument
An expression in the comma-separated list bounded by the parenthesis in a function call expression. 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 an array declaration that identifies the name of the array and the boundary of (the number of elements in) each dimension of the array. If more than one bound is given, the declarator declares a multidimensional array.
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.
asynchronous signal
A signal that can occur at any time during the execution of a C or C++ program, but is not synchronized with the activity of the program. Typically, the cause is a user action. The asynchronous signals supported by VisualAge C++ are SIGBREAK, SIGINT, and SIGTERM. See signal, synchronous signal.
attribute
(1) A named property of an entity or part. An attribute can represent a data member of the underlying class, a part in and of itself, or the return value of a member function. See graphic attributes.
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. Contrast with heap 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.
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