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- daemon
- A program that runs unattended to perform a service for other programs.
- data abstraction
- A data type with a private representation and a public set of operations. The C++
language uses the concept of classes to implement data abstraction.
- database
- (1) A systematized collection of data that can be accessed and operated upon by an
information processing system. (2) A collection of information such as tables, views, and
indexes.
- data definition
- (1) A program statement that describes the features or establishes the context of data.
(2) A definition that describes a data object, reserves storage for a data object, and can
provide an initial value for a data object. A data object appears outside a function or at
the beginning of a block statement. IBM.
- data identifier
- The part of a data access class that is mapped to a database table's key.
- data member
- A part of an object of class type that is itself an object of user-defined or built-in
type. See attribute.
- DBCS
- See double-byte character set.
- debug
- To detect, locate, and correct errors in a program.
- decimal constant
- (1) A numeric data type used in standard arithmetic operations. (2) A number containing
any of the digits 0 through 9. IBM.
- deck
- A line of child windows in a set canvas that is direction-independent. A horizontal deck
is equivalent to a row and a vertical deck is equivalent to a column.
- declaration
- (1) An expression that introduces a name to a program and specifies how the name is to
be interpreted. Also called a directive. (2) The mechanism for establishing a language
object. (3) In the AIX operating system, a description that makes a defined object
available to a function or a block. IBM. (4) In the C language, a description
that makes an external object or function available to a function or a block statement. IBM.
- declarator
- An identifier and optional symbols that declare a single function, object or data type
within a declaration. See array declarator, function declarator.
- declare
- To specify the interpretation that C++ gives to each identifier.
- default
- The property of a value, attribute, or option that is assumed when no alternative is
specified.
- default argument
- A default value associated with a function parameter. If a call to the function omits
this argument, the default value is used. Parameters with default arguments must not
appear to the left of parameters without default arguments. See argument.
- default class
- A class with preprogrammed definitions that can be used for simple implementations.
- default clause
- In a C or C++ switch statement, the keyword default, followed by a
colon and one or more statements. When the conditions of the specified case labels in the
switch statement do not hold, the default clause is chosen.
- default constructor
- (1) A constructor that takes no arguments. (2) A constructor for which all the arguments
have default values. See constructor, destructor.
- default implementation
- One of several possible implementation variants offered as the default for a specific
abstract data type.
- default initialization
- The initial value assigned to a data object by the compiler if no initial value is
specified by the programmer. The variables extern and static
receive a default initialization of zero, while the default initial value for the auto
and register variables is undefined.
- default operation class
- A class with preprogrammed definitions for all required element and key operations for a
particular implementation.
- define
- In the AIX operating system, to create an entry in the Customized Devices Database and
establish the parent device and the connection location. IBM.
- define directive
- A preprocessor statement that directs the preprocessor to replace an identifier or macro
invocation with a specified portion of code.
- definition
- (1) A data description that reserves storage and may provide an initial value. (2) A
declaration that allocates storage, and may initialize a data object or specify the body
of a function.
- degree
- The number of children of a node.
- delete
- (1) A C++ keyword that identifies a free-storage deallocation operator. (2) A C++
operator used to destroy objects created by operator new.
- demangling
- The conversion of mangled names back to their original source code names. During C++
compilation, identifiers such as function and static class member names are mangled
(encoded) with type and scoping information to ensure type-safe linkage. These mangled
names appear in the object file and the final executable file. Demangling (decoding)
converts these names back to their original names to make program debugging easier. See mangling.
- deque
- A queue that can have elements added and removed at both ends. A double-ended queue.
- dequeue
- An operation that removes the first element of a queue. See enqueue.
- derivation
- (1) The creation of a new or derived class from an existing base class. (2) The
relationship between a class and the classes above or below it in a class hierarchy.
- derived class
- A class that inherits from a base class. You can add new data members and member
functions to the derived class. You can manipulate a derived class object as if it were a
base class object. The derived class can override virtual functions of the base class.
- destructor
- A special member function that is used to destroy, or finalize, objects of its class
type. A destructor has no parameters, and no return type is specified. See constructor.
- device
- A computer peripheral or an object that appears to the application as such. X/Open,
I.
- dialog box
- A window that opens in response to some user-initiated event and indicates the choices
available to the user.
- digital audio
- Audio data that has been converted to digital form.
- digital video
- Visual data that has been converted to digital form..
- digital video device
- A full-motion video device that can record or play files (or both) containing digitally
stored video.
- digraph
- Two characters that are used to represent one unavailable character in a source program.
Digraphs are read as tokens during the preprocessor stage. See token,
trigraph.
- diluted array
- An array in which elements are deleted by being flagged as deleted, rather than by
actually removing them from the array and shifting later elements to the left.
- diluted sequence
- A sequence implemented using a diluted array.
- direct manipulation
- A user interface technique that lets a user start application functions by manipulating
objects. The user begins an action by moving the mouse pointer over an object and then
pressing and holding down the drag mouse button (mouse button 2 is the default for OS/2)
while dragging the selected object to a new location. The user then drops the object onto
the new location by releasing the mouse button. For this reason, direct manipulation is
also known as drag and drop.
- directive
- A control statement that directs the operation of a feature and is recognized by a
preprocessor or other tool. See statement.
- directory
- A type of file containing the names and controlling information for other files or other
directories. IBM.
- disassembly
- Assembler language for a program module for which the source code is not available.
Disassembly is only visible during debugging and can be seen through the Disassembly view
or the Disassembly pane of the Source view of the IDE.
- display
- To direct the output to the user's terminal. If the output is not directed to the
terminal, the results are undefined. X/Open.
- document component
- The basic unit of data exchange in the Compound Document Framework.
- do statement
- In C and C++, a looping statement that contains the word do followed by a
statement (the action), the word while, and an expression in parentheses (the
condition). IBM.
- double-byte character set (DBCS)
- A set of characters in which each character is represented by 2 bytes. Languages such as
Japanese, Chinese, and Korean, which contain more symbols than can be represented by 256
code points, require double-byte character sets. Because each character requires 2 bytes,
you need hardware and supporting software that are DBCS-enabled to enter, display, and
print DBCS characters. Contrast with single-byte
character set.
- double-precision
- Pertaining to the use of two computer words to represent a number in accordance with the
required precision. I, ANSI.
- doubleword
- A contiguous sequence of bits or characters that comprises two computer words and can be
addressed as a unit.
- drag after
- In Compound Document Framework, a target enter event that occurs in a container where
its orderedTargetEmphasis or mixedTargetEmphasis attribute is set and the current view is
name, text, or details.
- drag item
- A proxy for the object being manipulated.
- drag over
- In Compound Document Framework, a target enter event that occurs in a container when its
orderedTargetEmphasis attribute is not set and the current view is icon or tree view.
- dump
- To copy data in a readable format from main or auxiliary storage onto an external medium
such as tape, diskette, or printer. IBM.
- dynamic
- Pertaining to an operation that occurs at the time it is needed rather than at a
predetermined or fixed time. IBM.
- dynamic binding
- Resolution of a call to a virtual member function at run time.
- dynamic casting
- (C++ only) The conversion of a given expression to a specified type by means of the
dynamic_cast operator. This conversion is usually checked and performed at runtime.
- dynamic linking
- Linking on demand at run time. Contrast with static
linking.
- dynamic storage
- See automatic storage.
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