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Introduction to Pseudocode for IGCSE Paper 2

Jun 8, 2024

Introduction to Pseudocode for IGCSE Paper 2

Purpose of Pseudocode

  • Represents code in a language-like format.
  • Simplifies complex coding tasks.
  • Examines logic over syntax.
  • Fundamental for understanding various programming languages.
  • Flexible and adaptable to future languages.

Importance in IGCSE

  • Focuses on the logic and efficiency of the pseudocode.
  • Encourages the understanding of the code structure.

Components of Pseudocode

Basics Covered in Chapter One

  • Font Style and Size: Mono-spaced (fixed width).
  • Indentation: Indicates the start and end of code segments.
    • Indent by four spaces for code contained within a statement.
    • Two-space indentation for line continuation.
  • Case and Italics: Very precise.
    • Keywords: Always in uppercase.
    • Identifiers: Mixed case (e.g., NumberOfPlayers).
    • Meta variables: Hold simplified versions of statements.
  • Lines and Numbering: Code lines are consecutive and executed in order.
  • Comments: Use double slashes // to add non-executable explanations within the code.

Data Types and Variables

Atomic Type Names

  • Integer: Whole numbers.
  • Real: Numbers with fractional parts (decimals).
  • Char: Single characters (e.g., a, B).
  • String: Series of characters (e.g., Hello).
  • Boolean: True or false values.

Identifiers and Assignments

  • Identifiers: Can be variables, constants, procedures, and functions.
    • Must start with a letter.
    • Use camel case (e.g., numberOfPlayers).
  • Assignments: Use an arrow (<-) to assign values to variables.
    • Example: counter <- 0.

Operations in Pseudocode

Input and Output

  • Keywords:
    • INPUT to take user input.
    • OUTPUT to display output.
    • Can use READ and PRINT as alternatives to INPUT and OUTPUT.

Arithmetic Operations

  • Addition: +
  • Subtraction: -
  • Multiplication: *
  • Division: /

Logic Operators

  • AND, OR, NOT: Used in complex expressions.

Control Structures

If Statements (Selection Loop)

  • Basic structure: IF (condition) THEN (statement) ENDIF
  • Nested if statements: Multiple if statements within each other.

Case Statements

  • Used to handle multiple values of a variable.
    • Example: 
      CASE OF move
'W': statement1
'A': statement2
OTHERWISE: defaultStatement
END CASE

For Loop (Count-Controlled Loop)

  • Structure: FOR (variable) <- (value) TO (value) DO (statement) ENDFOR
  • Executes a set number of times.

Repeat Until Loop (Post-Condition Loop)

  • Structure: REPEAT (statement) UNTIL (condition)
  • Continues until the condition becomes true.

While Loop (Pre-Condition Loop)

  • Structure: WHILE (condition) DO (statement) ENDWHILE
  • Executes as long as the condition is true.

Arrays

Structure and Usage

  • 1D Arrays: Simple lists of elements indexed by position.
    • Example: studentNames: ARRAY[1..30] OF STRING
  • Assigning Arrays: Assign values to specific index positions in arrays.

Examples

  • studentNames[1] would access the first element in the array.
  • Arrays are used to manage lists of items.

Summary

  • Understanding pseudocode fundamentals helps in learning programming.
  • Practice with questions and real-life examples enhances comprehension.

Keywords and Symbols

  • Remember important keywords and symbols.
    • Example Keywords: INPUT, OUTPUT, IF, FOR, WHILE.
    • Symbols include arithmetic and logical operators.

Note: Detailed guides and practice questions will aid in mastering pseudocode.

End of Notes

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