R
 
redirect
To associate files with the input or output of commands.
reentrant
The attribute of a program or routine that allows the same copy of a program or routine to be used concurrently by two or more tasks.
reference class
A class that links a concrete class to an abstract class. Reference classes make polymorphism possible with the collection classes. See abstract class, concrete class, polymorphism.
reference counted object
an object that keeps track of the number of pointers that refer to it. This number is called the reference count.  See reference counting.
reference counting
The technique of keeping track of how many pointers refer to a given object. See reference counted object and counted pointer.
register
A storage area commonly associated with fast-access storage, capable of storing a specified amount of data such as a bit or address.
register storage class specifier
A specifier that indicates to the compiler within a block scope data definition or a parameter declaration that the object being described will be heavily used.
register variable
A variable defined with the register storage class specifier. Register variables have automatic storage.
regular expression
(1) A mechanism to select specific strings from a set of character strings. (2) A set of characters, metacharacters, and operators that define a string or group of strings in a search pattern. (3) A string containing wildcard characters and operations that define a set of one or more possible strings.
regular file
A file that is a randomly accessible sequence of bytes, with no further structure imposed by the system. X/Open, I.
relation
An unordered flat collection class that uses keys, allows for duplicate elements, and has element equality. See key access, unordered collection.
relational database
(1) A data structure organized so that it is perceived by its users as a collection of tables. (2) A database that is organized and accessed according to relations. T. A relational database has the flexibility to generate new tables from existing records that meet specified criteria.
renderer
An object that renders data using a particular mechanism, such as using files or shared memory. It contains definitions of supported rendering mechanisms and formats and types.
rendering
(1) The transfer or re-creation of the dragged object from the source window to the target window.
resource
(1) Any facility of a computing system or operating system required by a job or task, including main storage, input/output devices, the processing unit, data sets, and control or processing programs. (2) A binary data item that is linked to an executable file, a DLL, or some other binary file. Typically a resource defines an interface component such as a dialog box, a menu, an icon, a font, a bitmap, or a cursor. (3) Any element that requires translation, such as messages or online help.
resource file
A source file or compiled file that defines the resources that are used by an application. VisualAge C++ recognizes uncompiled resource files by the file extension .rc. A compiled resource file has the file extension .res.
response file
A file that acts as an extension of command-line input, providing options and parameters as input to a component.
return
A language construct that ends an execution sequence in a procedure. IBM.
return value
A scalar returned by a function that does not have type void.
REXX
Restructured Extended Executor. An IBM structured programming language used as a general-purpose macro language that sends commands to application programs and to the operating system.
RGB
Red, green, blue. A method of processing color images according to their red, green, and blue color content.
RMFs
Rendering mechanisms and formats.
root
In a tree structure, a node that has no parent. All other nodes of a tree are descendants of the root. See tree, node, child node, parent node.
RTTI
See run-time type identification.
run-time library
A compiled collection of functions whose members can be referred to by an application program during run-time execution. VisualAge C++ contains separate run-time libraries for C and C++.
run-time type identification (RTTI)
A mechanism in the C++ language for determining the class of an object at run time. It consists of two operators: one for determining the run-time type of an object (typeid), and one for doing type conversions that are checked at run time (dynamic_cast). A type_info class describes the RTTI available and defines the type returned by the typeid operator.
rvalue
(1) An expression that must appear on the right side of an assignment. (2) An expression that cannot have a value assigned to it. The result of calling a function that does not return a reference. Rvalues always have complete types or the void type. Contrast with lvalue.
IBM Copyright 2003