algorithms

• What is an algorithm?

  A set of rules/instructions to complete a task.
• How does Abstraction relate to Programming?

  Abstraction helps program by hiding technical details, simplifying complex problems, and focusing on essential features.
• Three basic control structures used in programming

  • Sequence
  • Selection
  • Iteration
• Three operators used in Boolean expressions

  • AND
  • OR
  • NOT
• Selection

  An IF statement is a selection statement. The next statement to be executed depends on whether the condition being tested is True or False.
• Comparison expressions

  The condition average >= 80 is a Boolean expression. The outcome will always evaluate to TRUE or FALSE.
• Comparison operators


  • ==
  • !=
  • >=
  • <=
• = is not used to mean equal to, as a single = is used for assignment
• If statements


  If statements allow different branches to be executed based on the result of a Boolean expression.
• Complex Boolean expressions

  Boolean expressions can include the Boolean operators AND, OR and NOT
• Switch/case statement

  This statement may be used when a selection is to be made from several alternatives, for example when choosing from a menu.
• Arithmetic operators

  • +
  • -
  • *
  • /
  • ^
  • MOD
  • DIV
• Variables

  Containers that store data values
• Data types of variables


  • Integer
  • Boolean
  • Real / Floating point number
  • Character
  • String
• Constants

  Values that cannot be changed during program execution
• Constants are typically shown in uppercase with words separated by an underscore
• Why declare a constant instead of a variable?

  • Prevents the value from being changed accidentally
  • Shows the programmer the value should stay the same
• A constant cannot be changed when the program is running, but can be changed by a programmer before the program is compiled or translated
• Input and output statements

  1. Accept data from the user

  2. Process the data

  3. Output the result
• INPUT statement

  Displays a prompt for the user and waits for their response, which is then assigned to a variable
• DIV


  Integer division, also known as quotient
• MOD

  Remainder when dividing one integer by another
• BIDMAS

  Order of precedence: Brackets, Indices, Division, Multiplication, Addition, Subtraction
• Strings and integers are represented differently in binary
• Conversions and casting

  Functions used to convert data types (int(), float(), str(), bool(), ASC(), CHR())
• Inputs from the user are strings, so they need to be converted before use in calculations
• Concatenating strings

  Joining strings together using the + operator
• String handling functions

  • length
  • substring
  • left
  • right
• ASC() and CHR()

  Convert characters to/from their ASCII values
• Uppercase and lowercase


  Converting strings to all uppercase or all lowercase using .upper() and .lower()
• Comments are used to describe the purpose, author, and explain the code
• Comments are ignored when the program is translated to machine code and executed