GCSE Computer Science Paper 2 Exam Summary

Flashcards of key vocabulary terms and definitions from the lecture notes.

Algorithm

A sequence of steps that can be followed to complete a task.

Algorithmic Thinking

Solving problems by defining steps and the sequence needed.

Pseudocode

Something resembling code, but it's often a bit more relaxed; how you do it doesn't really matter as long as it looks a bit like code.

Abstraction

Removing unnecessary detail from a problem.

Decomposition

Breaking down a problem into subproblems that each represent a specific task.

Trace Table

Shows how values change when an algorithm is actually carried out.

Linear Search

A search algorithm that compares each item in a list one by one until the target is found; there is no need for the list to be in order.

Binary Search

Works by comparing the middle item to your target item and discarding half of the list which the target can't be in; only works if the list is ordered.

Bubble Sort

Works by doing a series of passes, going through the list and swapping each pair if it needs to, repeating until a single pass happens with no swaps.

Merge Sort

Divides a list continuously by two until each list has one item in it only, and then merges the lists, combining two lists at a time, keeping the items in order as you do this.

Insertion Sort

Starts with one item in a sorted part and moves items one by one from your unsorted part to the sorted part.

Data Types

Determine how data is stored in the computer and also the operations it can do.

Real/Float Data Type

A fractional number.

String Data Type

Any value with quotes around it.

Casting

Converting between one data type to another.

Exponentiation

To the power of.

Quotient (div)

Integer division; does the division but always cuts off the fractional part.

Modulus (mod)

Gives you the remainder after division.

Substring

A string operation where you extract a portion of a string based on starting index and number of characters.

Concatenation

Putting two strings together.

Variable

Identifiers that hold a value that can be changed.

Constant

Same as variables, but they can't be changed once assigned a value.

Sequence

A block of code where two or more lines are executed line by line.

Selection

Using if statements to check conditions.

Iteration

Where some code will repeat (loops).

Count-Controlled Loop

A for loop that repeats a set number of times.

Condition-Controlled Loop

Loops that repeat until a condition is broken (while loop) or met (do until loop).

Subprogram/Subroutine

Named out-of-line blocks of code (procedure or function).

Procedure

A type of subprogram.

Function

A type of subprogram which has a return value.

Parameters

Variables used as an input to a subprogram.

Return Value

An output from a subprogram that is kept internal.

Local Variable

Only exists when the subprogram is executing and is only accessible inside of a subprogram.

Global Variable

Exists outside of a function.

Indentation

A gap at the start of a line; makes the code clearer to look at because you can easily see what lines of code belong to what block of code.

Comment

An annotation in code used to explain what code is doing to make it easier to understand.

Data Structure

Organized collections of items.

Array

Contains items of the same data type and is generally of a fixed or static length.

Indexing

Using a number to refer to a particular item in an array.

SQL

For interacting with databases; SQL select is used to search and retrieve data from tables.

2D Arrays

Useful for representing tables; an array of arrays.

Defensive Design

Trying to make your programs robust.

Iterative Testing

Testing specific modules while you are developing; repeatedly testing stuff until it is all perfect.

Terminal/Final Testing

Testing for a whole program right after development.

Syntax Error

Where you've not followed the rules of your language; the code won't even run.

Logical Error

If a code does not do as you intend; it does run, it just doesn't quite do what you want it to do.

Validation

Enforcing a rule around user input.

Authentication

Checking the identity of the user.

Boolean Logic

A separate topic with three Boolean operators, logic gate symbols, and associated truth tables.

NOT Gate

A triangle with a tiny circle at the end; flips the input.

AND Gate

Two inputs and one output; only one if both inputs are one.

OR Gate

Will only give you zero if both inputs are false.

High-Level Language

More readable and easier to code in; portable but slower to execute.

Low-Level Language

Assembly code and machine code; more control, easier to optimize, but specific to particular CPUs and harder to write.

Translator

A program that converts one language to another.

Compiler

Produces an executable file when you run it; fast to execute, but errors are only shown right at the end.

Interpreter

Translates an instruction then running it straight away; you see errors as soon as they happen, but users need to see the source code.

Integrated Development Environment (IDE)

Supports your programming with features like an editor, debugging tools, a runtime environment, and a translator.