Key Terms

Key Terms

abstract method

declared without a code block for implementation; the stubs of methods that will be implemented by a class which uses the interface

abstraction

way of thinking and expressing algorithms to indicate what the programmer wants the hardware to do

access modifier

keyword that denotes where in code to access a variable or method

argument

value of a function call, which must match the parameters in both number and data type

array

named variable that references a block of contiguous memory locations

array initializer

values separated by commas placed between curly braces

assembly

process of converting a low-level assembly language product of the compiler into machine language that the computer can execute; binary form

assignment statement

operation by which a value is stored in a variable

back end

compiler step that is responsible for code generation or production of the target code

basic block

minimal-length sequence of instructions that will always execute in its entirety if it executes at all, equivalent to a code block

best practice

most accepted style and structure of code that can be used to ensure proper software development, which makes it possible to learn new languages easily once a programmer has mastered a given one

binary operator

operator surrounded by two operands

Boolean

data types that can hold the values true or false

bottom-tested loop

condition for further loop iteration set at the exit from the code block

busy waiting

condition of a process that is continually looking to see if it has access to a critical section, taking processor time from all processes

bytecode

object code produced by Java compilation, which is then interpreted by the Java virtual machine

call stack

execution stack that is the data structure that controls the calling and return of functions

case-sensitive

refers to whether uppercase and lowercase letters are treated as distinct from each other

class

code blueprint from which objects are constructed

client-side script

script that runs on a client computer, usually under the control of a web browser and needs an interpreter on the client’s machine

code block

statement that consists of one or more statements that are structured in a sequential group and delineated as such

code generation

transformation of the code to the target or object language

coercion

ability of a variable of a data type to be forced to hold a value of a different data type

combined assignment

when the assignment operator is combined with another operator, usually mathematical, as a shortcut notation

comment

container used to hold documentation in code

Common Gateway Interface (CGI)

executable program residing in a special directory known to the web server management program

Common Language Runtime (CLR)

takes managed code and provides a JIT execution that allows all the languages to play nicely with each other

compilation

single process that takes the source code that the programmer creates and transforms it into another language

complex data type

data type consisting of multiple primitive types used as its building blocks

condition-controlled

loop that will continue to iterate until a specific condition is met

conditional expression

(also: Boolean expression) evaluates to the Boolean values of true or false

constructor

specialized method that is called upon to instantiate an object from a class

count-controlled

loop that will continue to iterate a specific number of times

decrement operator (--)

unary operator that lowers the value of its operand by one

destructor

specialized methods used in some languages to destroy an instantiated object and recover its memory

determinative

loop that is predictable in its number of iterations

dynamic linker

compilation process which allows the program to be carried over to memory for execution after it runs

dynamic method binding

all methods are resolved dynamically at runtime, not by the compiler, sometimes referred to as late binding

element

each “shelf” of an array that can hold a value of a data type

embedded script

script in which one language is embedded inside another

encapsulation

attributes and behaviors of classes and objects are self-contained and go along with them throughout their lifetime

event-driven

when behavior of programs is controlled by actions (events) which are listened for and then acted upon or handled

exception

unusual behavior that can be recovered using exception handling support the programming language provides

exponentiation operator (**)

operator that raises the value of one operand to the power of the second operand

expression

construct in a programming language that evaluates two values

first-class function

function that can be assigned as a value to a variable

floating point

data type consisting of a decimal number

flow of control

order in which, or if, the statements of a program are executed

for loop

particular loop construct that is top-tested and count-controlled

formal parameter

represent values that the function needs to receive to do its job

front end

compilation step that is responsible for the analysis of the source code

function

code sequence that is designed to perform a particular task

function call

code which invokes the function and passes to it values that may be needed for it to do its job

function signature

defines a function and informs the compiler or interpreter about the details that it needs to call upon that function and what it may return

functional programming

programming model in which the key concept is that programs are constructed by composing functions and applying them

garbage collection

process used to destroy unneeded objects and recover memory when there are no longer any references to them in the code

global optimization

code improvements at multiple layers that include loop performance improvement, register allocation, and instruction scheduling

high-order function

function that can take one or more first class functions as arguments

hybrid implementation

method of language translation which involves the use of both a compiler and an interpreter

identifier

name given to a variable or other construct

imperative language

emphasizes a “tell the computer what to do” approach

increment operator (++)

unary operator that raises the value of its operand by one

indexed array

array in which the elements are numbered with an index, starting at zero

information hiding

masking of the actual bits and bytes of implementation that the user of a module does not need to know

inheritance

feature of OOP in which classes and objects take on specified attributes from their ancestors

initialization

assigning its first value to a variable

instantiation

process of building an instance (an object) of a class

integer

data type consisting of whole numbers

interface

construct which resembles a class definition but contains only methods which are constructed as abstract methods

intermediate code

language translation phase that produces a code level between the source code and the object code

intermediate form (IF)

middle end compilation product created after semantic analysis if the program passes all checks

intermediate language

generated from programming source code, but the CPU typically cannot execute directly

iteration

looping, going around and re-executing sequences of statements

Java virtual machine (JVM)

Java interpreter that translates bytecode into executable code

just-in-time (JIT) compilation

process when intermediate code gets its final compilation (or usually interpretation) phase right at the start of runtime

just-in-time (JIT) translation

process in which intermediate language is translated and executed exactly when needed

keyword

word reserved by the language that has a special meaning

late binding

when all methods are resolved dynamically at runtime, not by the compiler; sometimes referred to as dynamic binding

lexical analysis

compilation step that converts the source code strings of characters into tokens

literal

value of one of the legal data types of an HLL that can be written directly into the code

local optimization

elimination of redundant operations in a basic block

lvalue

left-hand operand in an expression

managed code

code targeted to run under a particular runtime environment

member

attribute or method that is encapsulated within a class or object

metadata

data about data

middle end

compilation step responsible for performing optimizations of the code

modularization

splitting a large job into independent units which may be then called upon to perform tasks

module

component of a program

modulo operator (%)

operator which evaluates to the remainder left after division

multiple inheritance

ability to inherit attributes and methods from more than one parent

multitask

ability of an application to process more than one task at the same time or to engage in concurrency

mutable

something that is changeable, possibly referring to state

name-value pair

construct-like variables that is named and can hold values

named constant

container that can be assigned the value of a data type which may not be changed thereafter

non determinative

loop for which we cannot predict the number of iterations (condition controlled)

object code

machine code produced by a compiler or interpreter

operator

performs various types of operations (processes) on values

optimization

producing what will be needed to generate the fastest and most efficiently running code possible

override

define another method with the same name and modify its signature

parallelism

when programs can have more than one part of the code running simultaneously

parsing

front-end compilation process, also referred to as syntax analysis, or reading the code to make sure it conforms with the syntax rules of the language

pass by reference

actual memory address of a variable passed as an argument, meaning the function has access to modify the original variable

pass by value

copy made of a value and passed as an argument, meaning the function has no access to modify the original variable

polymorphism

feature of OOP in which methods inherited may perform in different ways in different subclasses and depend upon their context

precedence

order of operations rules that determine the order in which operators in statements are evaluated

preprocessing

pre-compilation step in which the source code is manipulated to prepare it for the compilation stage

preprocessor directive

code that describes resources the program needs in order to compile, usually files to insert into the source code

primitive data type

(also: basic data type) simplest data type of a language that can usually be represented directly by the hardware memory and registers

procedural language

allows programmers to group statements into blocks of code within the scope of which variables may be defined and manipulated independently from the rest of a program

public interface

documentation of only what a user needs to access an object, its attributes, and its methods

pure function

function that will return the same result every time given the same arguments

race condition

when the condition of a program and its behaviors are not synchronized

readability

measures how easily an HLL can be read and understood

reference variable

variable that holds memory addresses

return

command that ends a function and/or sends values back to the place at which the function was called

runtime error

exception that is serious enough that it cannot or should not be handled by the software

rvalue

right-hand operand in an expression

scope

defines both the visibility of variables to locations in the code and the physical lifetime of variables

scripting language

characterized by placing a list of code statements into a file, referred to as a script

selection

making a decision on which path of execution to follow

semantic analysis

compilation step that discovers the meaning of the code

sentinel

expression that sets the condition at the entry or exit of a loop for continued iteration

separate compilation

situation where pieces of the program can be compiled and independently built

sequential execution

executing statements in the order in which they appear

server-side script

script that runs on a server in a web designer’s domain

shared data

data available to multiple program locations and/or scopes

shell scripting

stringing together a group of commands to perform tasks on the user interfaces of various operating systems

short circuiting

when HLL expressions that use the logical operators do not need the second operand evaluated for results to be known

single inheritance

methodology used by most modern OOP HLLs in which classes and objects can only inherit from one parent

stack frame

structure representing a function and its parts that is placed on the call stack

stack overflow

condition in which the call stack has run out of memory in which to expand

starvation

condition of a process when a process must wait to enter a critical section, but the other processes monopolize the section, and the waiting process does not get processor time

state

data that are remembered over time

static linker

produces an executable object file by completing its tasks prior to the program running

string

data type representing a sequence of characters

strongly typed

language in which a variable may only contain one of the language’s defined data types for its entire existence

Structured Query Language (SQL)

most widely used language to specify a query that a database system can process to store or retrieve data

subclass

child class in an inheritance relationship

superclass

parent class in an inheritance relationship

syntax analysis

front-end compilation process usually referred to as parsing or reading the code to make sure it conforms with the syntax rules of the language

ternary operator

acts on three operands

thread of control

thread the processor is controlling, which is actually executing at the time

tokens

front-end compilation product that are sequences of compiler recognizable atomic symbols which make it much easier for the next steps to recognize them

top-tested loop

when a condition for further loop iteration is set at the entrance to the code block

truth table

chart that shows what the resulting value would be given every combination of values of operands in an expression using a logical operator

type cast

operation that coerces an assignment of a possibly incompatible data type to a variable

unary operator

acts on one operand

user interface (UI)

point at which human users interact with a computer, website or application

variable

gives a name to a memory location that is used in any HLL to hold a value

variable declaration

consists of a statement which specifies the variable name and data type

void

a keyword in many HLLs that denotes a null value stored in a variable or that a function returns no value

weakly typed

when a variable may at different times hold values of any of the language data types

writability

measures how easily an HLL can be used to create and modify programs