4.1 Fundamentals of Programming AQA Comp Sci

A-Level

Integer

whole numbers

Real/Float

Decimal numbers

Boolean

True or False (1 or 0)

Character

A single symbol

String

A sequence of characters

Date/Time

Stores date and time values

Point/Refrence

Holds memory address of a variable

Record

A structured data type, similar to a dictionary

Array

A collection of elements of the same type

List

An array that can be comprised of multiple data types

Arrays vs Lists vs Tuples

Lists are dynamic, mutable with multiple data types

Arrays are fixed, mutable with a single data type

Tuples are fixed, immutable and hold a single data type

Variable Declaration

Declaring the name of a variable

Constant Declaration

Declaring the name of a constant

Assignment

Assigning a value to a variable or constant

Iteration

Repeats a block of code multiple times

Definite Iteration

Iterates for a certain number of values (i.e. for loop)

Indefinite Iteration

Iterates for an unknown number of times (i.e. while loop)

Subroutine

Block of reusable code available when called

Nested Structure

A programming structure where one structure is contained within another

Truncation

Removes the decimal part of a number without rounding

Ceiling

rounds a number up to the nearest integer

Floor

rounds a number down to the nearest integer

Local Variables

Declared inside a function, exist only within the function, cannot be accessed from outside

Advantages of Local Variables

Saves memory as created and destroyed when needed, prevents unintended modification

Global Variable

Declared outside all functions, accessible throughout the program

Disadvantages of Global Variables

makes debugging harder, can accidentally override values, functions become less reusable

A Stack Frame consists of

Return Address, Contents of Registers, parameters to be passed, local variables

Base Case (Recursive Techniques)

The condition which stops recursion

Recursive Case

The function calls itself

Recursion

Where a function calls itself to solve a problem by breaking it down into smaller, more manageable parts

Advantages of Recursion

simplifies problem, more elegant and easier to read

Disadvantages of Recursion

High memory usage, can lead to stack overflow, iterative solutions often more efficient

Programming Paradigms

Ways to classify programming based on their methodology, including object-oriented, functional, and procedural.

Procedural-Oriented Programming

Uses sequential execution, selection, and iteration to control flow of program.

Advantages of Procedural Programming

easy to debug and modify, easy to write and understand, reusable functions improve efficiency, good for tasks that have a clear sequence of operations

Disadvantage of Procedural Programming

harder to maintain for large-scale projects, code reusability is limited compared to OOP

Object-Oriented Programming (OOP)

Organises code around data or objects, rather than functions and logic.

Class (OOP)

A blueprint for creating objects, containing attributes and methods.

Attribute (OOP)

Properties of a class (values)

Method (OOP)

Subroutines inside a class that can be called

Object (OOP)

An instance of a class allocated in memory

Instantiate (OOP)

To create an instance of an object, stored inside a variable

Inherit (OOP)

To build a relationship between similar classes.

Parent (OOP)

A super class of a child.

Chid (OOP)

A sub class of a parent - inherits the same attributes and methods

Encapsulation (OOP)

Bundling of data into a class with the methods that operation on that data, using getters and setters. Hides values within the class to protect them from outside interference.

Private (OOP)

Components that can only be seen and changed in the class

Protected (OOP)

Components that can only be seen and changed in the class, or subclasses of that.

Public (OOP)

Components that can be seen and changed anywhere in the code

Polymorphism (OOP)

Enables objects of different classes to be treated as objects of a common superclass, allowing methods to perform differently based on the object's actual class.

Overriding (OOP)

When a subclass provides as specific implementation of a method that is already defined in the parent class, replacing the base functionality.

Association (OOP)

A general relationship between classes that doesn’t imply ownership.

Aggregation (OOP)

A type of relationship between two classes where one has a reference but can exist independently.

Composition (OOP)

A stronger form of association where the class cannot exist without another (Death Relationship)

Abstract Method (OOP)

A method defined in an abstract class that has no implementation.

Virtual Method (OOP)

A method in a base class that is intended to be overridden in child classes.

Static Method (OOP)

A method that belongs to the class itself, rather than any instance of a class. Static methods can be called without creating an instance.

Interface (OOP)

A skeleton or outline of a class where methods are defined but not implemented.

Composition in Class Diagrams

black diamond

Aggregation in Class Diagrams

white diamond

Public, Private, Protected - Class Diagrams

+, -, #