Pseudo Code for Factorial Calculation Using REPEAT-UNTIL Loop

This document outlines the pseudo code for calculating the factorial of a non-negative integer using a REPEAT-UNTIL loop. The factorial of a non-negative integer n is defined as the product of all positive integers less than or equal to n, denoted as n!.

Inputs

• A non-negative integer n

Outputs

• The factorial value of n, denoted as factorial

Pseudo Code Structure

1. Initialize the variable factorial to 1
2. Initialize the variable counter to 1
3. Use a REPEAT-UNTIL loop to calculate the factorial

Pseudo Code

BEGIN
    // Step 1: Get input from the user
    PRINT "Enter a non-negative integer n:"
    INPUT n
    
    // Step 2: Validate input
    IF n < 0 THEN
        PRINT "Error: Factorial is not defined for negative integers."
        RETURN

    // Step 3: Initialize variables for REPEAT-UNTIL loop
    SET factorial = 1
    SET counter = 1

    // Step 4: REPEAT-UNTIL loop for factorial calculation
    REPEAT
        factorial = factorial * counter
        counter = counter + 1
    UNTIL counter > n

    // Step 5: Output the result
    PRINT "The factorial of", n, "is", factorial
END

Explanation of the Pseudo Code

• Input Handling: The user is prompted to enter a non-negative integer. Input validation is performed to ensure the value is valid (non-negative). If invalid, an error message is displayed.

• Initialization: Two variables are initialized:

  • factorial is initialized to 1 (as any integer multiplied by 1 remains unchanged).
  • counter is initialized to 1 (to start the multiplication from the first positive integer).

• REPEAT-UNTIL Loop:

  • The loop continues until counter exceeds n.
  • Within each iteration, the current value of counter is multiplied to factorial, effectively accumulating the product.
  • The counter is then incremented by 1 until the loop condition is no longer met.

• Output: Once the loop concludes, the calculated factorial is printed.

This pseudo code provides a straightforward approach to calculating the factorial using a REPEAT-UNTIL loop, ensuring clarity and ease of understanding for users or developers. For deeper insights into programming concepts, consider exploring courses on the Enterprise DNA Platform.