2.2 Programming fundamentals

Variable Declaration

Creates a variable to store data.

Constant Declaration

A value that does not change while the program runs. Often given fully uppercase identifiers.

Assignment

Setting or updating a value in a variable.

Input

Receiving data from the user.

Output

Displaying data or information to the user.

Sequence

Instructions executed in order.

Selection

Decisions (IF, ELSE).

Iteration

Repetition (WHILE, FOR).

Arithmetic Operations

The basic mathematical calculations that can be performed in a programming language.

Addition

Operation symbol: +, Example: 3 + 2, Result: 5.

Subtraction

Operation symbol: -, Example: 7 - 4, Result: 3.

Multiplication

Operation symbol: *, Example: 5 * 3, Result: 15.

Real Division

Operation symbol: /, Example: 10 / 4, Result: 2.5.

What does the modulus operation (MOD) find?

The remainder when one number is divided by another number.

What is the operation symbol for modulus?

%

What is the result of the operation 5 % 2?

1

What is the definition of a quotient?

The number we obtain when we divide one number by another.

What is the operation symbol for division in programming?

//

What is the result of the operation 8 // 3?

2

Exponentiation

Operation symbol: ^, Example: 4^2, Result: 16.

Comparison Operations

Used to compare different items of data, returning True or False.

Equal to

Operation symbol: ==, Example: 5 == 5, Result: True.

Not equal to

Operation symbol: !=, Example: 3 != 4, Result: True.

Less than

Operation symbol: <, Example: 2 < 5, Result: True.

Greater than

Operation symbol: >, Example: 6 > 7, Result: False.

Less than or equal to

Operation symbol: <=, Example: 5 <= 5, Result: True.

Greater than or equal to

Operation symbol: >=, Example: 7 >= 10, Result: False.

Boolean Operations

Logical operators that work with Boolean values (True or False).

NOT

Reverses the Boolean value.

AND

Returns True if both input conditions are true.

OR

Returns True if either input condition is true.

Data Types

Defines the kind of data a variable or constant can hold.

Integer (int)

Whole numbers only, no decimals.

Real (float)

Numbers that include a fractional/decimal part.

Boolean (bool)

Often used for conditions and logic, can be True or False.

Character (char)

A single symbol or letter, must be enclosed in quotation marks.

String (str)

A sequence of characters.

Integer

A data type representing whole numbers.

String

A data type representing a sequence of characters.

Casting

Changing data types of a variable, for example from integer to string.

String Manipulation

Refers to measuring the length of strings, concatenating strings or slicing strings.

Length

Returns the number of characters in a string.

subString

Extracts a sequence of characters within a string.

Concatenation

Joins strings together.

File Handling

Refers to the reading or writing to or from an external file.

Read Mode

A mode in which a file is opened for reading.

Write Mode

A mode in which a file is opened for writing.

Data Structure

A way of organising and storing related data so it can be used efficiently in a program.

Record

A data structure used to group different types of data under one structure.

Array

A fixed-size data structure with a collection of similar data items stored under a single name.

One-Dimensional Array (1D)

A single list of items.

Two-Dimensional Array (2D)

An array of arrays, like a database table or grid.

Database

Used to store large amounts of data into organised tables.

Structured Query Language (SQL)

A language used to search for, manage, and manipulate data in a database.

SELECT

An SQL command used to specify the data to be retrieved.

FROM

An SQL command used to specify the table from which to retrieve data.

WHERE

An SQL command used to specify conditions for data retrieval.

SELECT command

Used to retrieve information about a particular field in a database.

FROM command

Refers to the database being searched.

WHERE command

Used to apply conditions to a search.

SQL command structure

Takes the form: SELECT FROM WHERE .

Wildcard * in SQL

Used to represent all fields in the SELECT command.

Subprogram

A section of code which performs a specific task, and can be called whenever it is needed.

Functions

A type of subprogram that performs a task and returns a value.

Procedures

A type of subprogram that performs a task and does not return a value.

Parameters

Values which can be passed into a subprogram when it is called.

Local variables

Defined inside of a subprogram and can only be used inside of that subprogram.

Global variables

Defined in the main program and can be used anywhere, including all subprograms.

Why use Subprograms?

They make code more structured and modular, allow code to be reused, make programs easier to test and maintain, and allow shared workload.

Random Number Generation

The ability to produce unpredictable numeric values within a specified range.

RANDOM_INT function

Used to generate a random integer within a specified range.

random.randint function in Python

Generates a random integer within a specified range, inclusive of the endpoints.

Typical Uses of Random Number Generation

Rolling a die, picking a random question or card, generating test values for simulations, and randomly deciding outcomes in games.

Good Practice for Random Number Generation

Store the random value in a variable if it will be used more than once.