Pseudocode (meaning "fake code") is a method for representing an algorithm using an informal, high-level description of its logic. It's written for humans to read, not for computers to execute. It uses the structural conventions of a programming language, like IF, FOR, and WHILE, but omits the strict syntax rules.

·         Advantages: It's quick to write, easy to understand, and simple to modify. It allows the programmer to focus purely on the algorithm's logic without worrying about the specifics of a programming language.

·         Disadvantage: It's not standardized. Different programmers might use slightly different styles.

Common Keywords & Constructs

While there are no strict rules, several keywords and constructs are commonly used to represent different actions in pseudocode.

Examples in Pseudocode

1. Basic Example (Sequential Logic)

·         Problem: Calculate the area and perimeter of a square given one side.

·         Logic: The algorithm takes the side length as input, applies the formulas for area (side2) and perimeter (4×side), and prints both results.

START

  // Get input from the user

  READ side

  // Perform calculations

  SET area = side * side

  SET perimeter = 4 * side

  // Display the results

  PRINT "Area is:", area

  PRINT "Perimeter is:", perimeter

END

2. Moderate Example (Conditional Logic)

·         Problem: Check if a number is positive, negative, or zero.

·         Logic: This requires a chain of IF-ELSE IF-ELSE conditions to check the number against zero.

START

  // Get input

  READ number

  // Check the conditions

  IF number > 0 THEN

    PRINT "The number is Positive."

  ELSE IF number < 0 THEN

    PRINT "The number is Negative."

  ELSE

    PRINT "The number is Zero."

  ENDIF

END

3. Advanced Example (Iterative Logic)

·         Problem: Check if a given positive number is a prime number.

·         Logic: A prime number is only divisible by 1 and itself. The algorithm checks for any divisors from 2 up to the number's square root. A flag variable is used to keep track of whether a divisor is found.

START

  READ number

  // Assume the number is prime until proven otherwise

  SET isPrime = true 

  // Handle base cases: 0 and 1 are not prime

  IF number <= 1 THEN

    isPrime = false

  ELSE

    // Loop from 2 up to the square root of the number

    FOR i from 2 to SQRT(number) DO

      IF (number % i) == 0 THEN

        // A divisor was found, so it's not a prime number

        isPrime = false

        BREAK // Exit the loop early

      ENDIF

    ENDFOR

  ENDIF

  // Print the final result based on the flag

  IF isPrime == true THEN

    PRINT number, "is a prime number."

  ELSE

    PRINT number, "is not a prime number."

  ENDIF

END