P
pack
  To store data in a compact form in such a way that the original form can be recovered.
pad
  To fill unused positions in a field with data, usually 0's, 1's, or blanks.
parameter
  (1) In the C and C++ languages, an object declared as part of a function declaration or definition that acquires a value on entry to the function, or an identifier following the macro name in a function-like macro definition. X/Open. (2) Data passed between programs or procedures. IBM.
parameter declaration
  A description of a value that a function receives. A parameter declaration determines the storage class and the data type of the value.
parent node
  A node to which one or more other nodes are subordinate. See child node, root.
parent process
  (1) The program that originates the creation of other processes by means of spawn or exec function calls. (2) A process that creates other processes.
parent window
  A window that provides its child windows with information on how and where to draw themselves. The parent window defines the relationship that the child windows have with other windows in the system. See child window, owner window.
path name
  (1) A string that is used to identify a file. It has an optional beginning slash, followed by zero or more file names separated by slashes. If the path name refers to a directory, it may also have one or more trailing slashes. Multiple successive slashes are considered to be the same as one slash. A path name that begins with two successive slashes may be interpreted in an implementation-dependent manner, although more than two leading slashes will be treated as a single slash. (2) A file name specifying all directories leading to the file.
pattern
  (1) A sequence of characters used either with regular expression notation or for path name expansion, as a means of selecting various character strings or path names, respectively. The syntaxes of the two patterns are similar, but not identical. X/Open. (2) A recognizable shape, form, or configuration. IBM. (3) In computer graphics, a combination of toned and untoned picture elements (pels) that make up an image. (4) A regular expression that defines a search pattern. (5) In AIX graphics, a 16x16, 32x32, or 64x64 array of bits defining the texturing of polygons on the system display. IBM.
pause
  To temporarily halt the medium. The halted visual should remain displayed but no audio should be played.
pel
  See pixel.
pipe
  To direct data so that the output from one process becomes the input to another process. The standard output of one command can be connected to the standard input of another with the pipe operator (|). Two commands connected in this way constitute a pipeline. IBM.
pixel
  Picture element. The smallest area of a display screen capable of being addressed and switched between visible and invisible states.
pointer
  A variable that holds the address of a data object or function.
pointer class
  A class that implements pointers.
pointer to member
  An operator used to access the address of nonstatic members of a class.
polymorphic function
  A function that can be applied to objects of more than one data type. C++ implements polymorphic functions in two ways:
  1. Overloaded functions (calls are resolved at compile time)
  2. Virtual functions (calls are resolved at run time)
polymorphism
  The technique of taking an abstract view of an object or function and using any concrete objects or arguments that are derived from this abstract view.
port
  To adapt an application for use with another operating system. Contrast with migrate.
portable character set
  The set of characters specified in POSIX 1003.2, section 2.4. See character set, Portable Operating System Interface.
Portable Operating System Interface
  (1) A set of operating system portable interface standards defined by the Institute of Electrical and Electronic Engineers (IEEE). Now an ISO/IEC international standard (ISO/IEC 9945). (2) An IEEE 1003.1 standard that defines the language interface between application programs and the UNIX operating system.
portability
  The ability of a programming language to compile successfully on different operating systems without requiring changes to the source code.
positioning property
  The property of an element that is used to position the element in a collection. For example, the value of a key may be used as the positioning property.
POSIX
  See Portable Operating System Interface.
pragma
  A preprocessor directive that is not specified by the ANSI standard. Pragmas often control actions of the compiler and linker. A pragma always begins with a number sign (#).
precedence
  The priority system for grouping different types of operators with their operands.
precondition
  A condition that a function requires to be true when it is called.
predefined function
  See built-in function.
predefined macro
  A frequently used routine provided by an application or language for the programmer. See macro.
predicate function
  A function that returns an IBoolean value of true or false. (IBoolean is an integer-represented Boolean type.)
preemptive multitasking
  The operating system's ability to interrupt a thread at almost any time and assign the processor to a waiting thread. Multiple applications can thus run simultaneously, and a single application cannot monopolize all of the system's resources. See multitasking.
preparation
  Any activity that the source performs before rendering the data. For example, the drag item may require that the source create a secondary thread where the source rendering takes place. The system remains responsive to users so that they can do other tasks.
preprocessor
  A phase of the compiler that examines the source program for preprocessor statements, which are then executed, resulting in the alteration of the source program.
preprocessor directive
  In C and C++, a statement that begins with the number sign (#) and contains instructions that the preprocessor interprets.
preroll
  To prepare a device to begin a playback or recording function with minimal delay.
primary expression
  A literal, name, or name qualified by the scope resolution operator (::).
primary source file
  A source file defined for a build in the configuration file. Each primary source file is processed only once during a compilation. See source file, included source file.
primary thread
  The first thread created when a process is initialized. See thread.
primitive
  See graphic primitive.
primitive attribute
  A specifiable characteristic of a graphic primitive. See graphic attributes.
priority queue
  A queue that has a priority assigned to its elements. When accessing elements, the element with the highest priority is removed first. A priority queue has a largest-in, first-out behavior. See queue.
private
  Pertaining to a class member that is accessible only to member functions and friends of that class. Contrast with protected, public.
process
  (1) A collection of code, data, and other system resources, including at least one thread of execution, that performs a data processing task. (2) A running application, its address space, and its resources. (3) An instance of a running program. A Win32 process owns a 4-GB address space containing the code and data for an application's executable file; it does not execute anything. It also owns certain resources, such as files, dynamic memory allocations, and threads. (4) A program running under the OS/2 operating system, along with the resources associated with it (memory, threads, file system resources, and so on).
profiling
  The process of generating a statistical analysis of a program that shows processor time and the percentage of program execution time used by each procedure in the program.
program
  (1) One or more files containing a set of instructions conforming to a particular programming language syntax. (2) A self-contained, executable module. Multiple copies of the same program can be run in different processes.
program group
  In Windows NT, a window displaying a group of programs.
program heap
  See free store.
project-scoped action
  An action that applies to a project as a whole, or to a project's specially designated parts. Specially designated project parts are the project's makefile and target. An example of a project-scoped action is debugging, which is invoked on the project's target.
property function
  A function that is used to determine whether the element it is applied to has a given property or characteristic. A property function can be used, for example, to remove all elements with a given property.
protected
  Pertaining to a class member that is only accessible to member functions and friends of that class, or to member functions and friends of classes derived from that class. Contrast with private, public.
prototype
  A function declaration or definition that includes both the return type of the function and the types of its arguments. See function prototype.
public
  Pertaining to a class member that is accessible to all functions. Contrast with private, protected.
pure virtual function
  A virtual function that has a function initializer of the form = 0;