Pseudocode help

Pseudocode cheat sheet

1. What is Pseudocode?

Pseudocode is a simplified, structured way of describing a program's logic without using strict programming language syntax. It focuses on clarity and problem-solving, rather than technicalities.

2. General Rules for Writing Pseudocode

  • Be simple and clear: Use plain English combined with programming constructs.
  • Consistent indentation: Indent to show hierarchy and structure (e.g., inside loops or conditions).
  • Avoid language-specific syntax: Stick to general terms like OUTPUT instead of print.
  • Use capitals for keywords: Make control structures (e.g., IF, ELSE, WHILE) stand out.

3. Common Constructs and Syntax

a. Input and Output

  • Input from the user:

    INPUT variableName

  • Example:

    INPUT userName

  • Output to the screen:

    OUTPUT "Message or value"

    Example:

    OUTPUT "Hello, World!"

b. Variables and Assignment

  • Assign a value to a variable:
    variableName ← value
    Example:
    score ← 0

c. Selection (IF Statements)

  • Basic IF structure:

    IF condition THEN
        statement(s)
ENDIF

    Example:

    IF score > 50 THEN
        OUTPUT "You pass!"
ENDIF

  • IF-ELSE structure:

    IF condition THEN
        statement(s)
ELSE
    statement(s)
ENDIF

    Example:

    IF age ≥ 18 THEN
        OUTPUT "You are an adult."
ELSE
    OUTPUT "You are not an adult."
ENDIF

d. Loops

  • FOR Loop:

    FOR variable ← start TO end
        statement(s)
NEXT variable

    Example:

    FOR i ← 1 TO 10
    OUTPUT i
NEXT i

  • WHILE Loop:

    WHILE condition
        statement(s)
ENDWHILE

    Example:

    WHILE score < 100
        score ← score + 10
ENDWHILE

  • REPEAT-UNTIL Loop:

    REPEAT
        statement(s)
UNTIL condition

    Example:

    REPEAT
        guess ← INPUT
UNTIL guess = answer

e. Procedures and Functions


Procedure (no return value):

  • PROCEDURE procedureName(parameters)
        statement(s)
ENDPROCEDURE

    Example:

    PROCEDURE greet(name)
        OUTPUT "Hello, " + name
ENDPROCEDURE

  • Function (with return value):

    FUNCTION functionName(parameters)
        statement(s)
    RETURN value
ENDFUNCTION

    Example:

    FUNCTION square(number)
        RETURN number * number
ENDFUNCTION

f. Arrays

  • Declaring an array:

    arrayName ← [value1, value2, value3]

    Example:

    scores ← [10, 20, 30]

  • Accessing array elements:

    OUTPUT arrayName[index]

    Example:

    OUTPUT scores[1]  // Outputs 10 (arrays are 0-indexed)

  • Modifying an array element:

    arrayName[index] ← newValue

    Example:

    scores[2] ← 25

4. Example: Complete Program

Problem: Write pseudocode to calculate the average of 5 numbers entered by the user.

total ← 0
FOR i ← 1 TO 5
    OUTPUT "Enter a number:"
    INPUT num
    total ← total + num
NEXT i
average ← total / 5
OUTPUT "The average is:", average

Tips for Exam Success

  1. Understand the problem: Break it into smaller steps before writing pseudocode.
  2. Practice regularly: Try converting algorithms into pseudocode.
  3. Check your work: Ensure your pseudocode follows logical flow and solves the problem.
  4. Use the marks: Look at how marks are distributed to ensure you've covered all steps.