NEB 12 Computer Science key terms

A finite, ordered set of unambiguous steps that transforms given inputs into a desired output and terminates. It must be precise enough that anyone following it reaches the same result.

A diagram that uses standard symbols such as ovals for start and end, parallelograms for input and output, rectangles for processes, and diamonds for decisions to show the sequence of steps in a solution.

A structured, English-like way of writing an algorithm that uses indentation and keywords such as IF, WHILE, and READ instead of strict syntax, so logic can be planned before coding.

A program that translates an entire source program into machine code before it runs, reporting syntax errors for the whole file and producing an executable that runs independently of the compiler.

A program that translates and executes source code one statement at a time, stopping at the first error it meets. It needs no separate executable file and is useful for testing small programs.

The human-readable program text written by a programmer in a high-level language such as C or Python, which must be translated before the processor can execute it.

A mistake that breaks the grammar rules of a programming language, such as a missing semicolon or unmatched bracket. The translator refuses to produce output until it is corrected.

A fault that occurs while a program is executing, such as division by zero or reading past the end of an array. The syntax is valid, but execution halts abnormally.

A flaw in the reasoning of a program that lets it run to completion but produce wrong results, for example using addition where multiplication was intended. It is found by testing, not by the compiler.

Manually tracing a program or algorithm with sample values, recording each variable in a trace table, to confirm the logic and locate errors without running the code on a computer.

A named storage location in memory whose value can change during execution. Its name identifies it, its data type fixes what it can hold, and its scope fixes where it is visible.

A named value that is assigned once and cannot be altered while the program runs, such as PI or MAX_SIZE. It makes programs easier to read and safer to modify.

A classification that determines which values a variable may hold and which operations apply to it, for example integer, real, character, string, and Boolean.

Converting a value from one data type to another, either implicitly by the translator or explicitly by the programmer, as when an integer is converted to a real number.

A control structure that tests a condition and executes one block of statements when it is true and optionally another block when it is false, allowing a program to choose between paths.

A control structure that repeats a block of statements while a condition holds or for a fixed number of times, avoiding the need to write the same instructions repeatedly.

A loop placed inside the body of another loop. The inner loop completes all its repetitions for each single repetition of the outer loop, which suits tables and two-dimensional arrays.

A collection of elements of the same data type stored in consecutive memory locations and accessed by an index, usually counted from zero in languages like C and Java.

The integer position used to locate a particular element of an array or string. In most languages the first element has index zero, so the last index is one less than the size.

A named block of statements that performs a task, may receive parameters, and may return a value. It lets a program reuse code instead of duplicating it.

A variable declared in a function's definition that receives a value when the function is called, letting the same code work on different data each time.

The single result a function sends back to the statement that called it, using a return statement. A function without a return value is often called a procedure.

A technique in which a function calls itself on a smaller version of the same problem, with a base case that stops the calls. Without a base case it recurses forever.

Repetition of a set of statements using a loop rather than a recursive call. It usually uses less memory than recursion because no new call frames accumulate.

An expression that evaluates to either true or false, built with relational operators such as < and = and combined with AND, OR, and NOT to control selection and loops.

A sequence of characters treated as one value, such as a name or address. Strings support operations like length, concatenation, comparison, and extraction of substrings.

A search that examines array elements one by one from the start until the target is found or the list ends. It works on unsorted data but is slow on large lists.

A search that repeatedly halves a sorted array, comparing the target with the middle element and discarding the half that cannot contain it. It is much faster than linear search.

A sorting algorithm that repeatedly compares adjacent elements and swaps them when out of order, so larger values gradually move to the end of the list over successive passes.

A sorting algorithm that finds the smallest remaining element and swaps it into the next position, building a sorted section from the front of the list one item at a time.

A measure of how the running time of an algorithm grows as the input size increases, usually written in Big-O notation such as O(n) for linear and O(log n) for binary search.

A linear data structure that follows last in, first out order, with push to add at the top and pop to remove from the top. It is used for undo, expression evaluation, and function calls.

A linear data structure that follows first in, first out order, with enqueue adding at the rear and dequeue removing from the front. It models waiting lines and print jobs.

An organised collection of related data stored so that it can be retrieved, inserted, updated, and deleted efficiently, usually managed by a database management system.

A field or combination of fields that uniquely identifies each record in a table. It cannot be null and cannot repeat, so it guarantees that rows are distinguishable.

A field in one table that holds the primary key value of a record in another table, creating a link between the tables and enforcing referential integrity.

Structured Query Language, used to define and manipulate relational data with statements such as SELECT, INSERT, UPDATE, DELETE, and CREATE TABLE.

The process of organising tables to reduce duplicated data and update anomalies by splitting them into related tables, typically through first, second, and third normal forms.

System software that manages hardware, memory, files, and processes, and provides services so application programs can run. Examples include Windows, Linux, and Android.

Programs that maintain and protect a computer system, such as antivirus tools, disk defragmenters, backup utilities, and file compression tools. They support rather than run user tasks.