Procedural Programming (OCR A Level Computer Science): Revision Note

Procedural Programming

What is procedural programming?

• Procedural programming is a method of writing software where tasks are broken down into a sequence of step-by-step instructions

  • Modular design:

    • It focuses on grouping code into functions and procedures to promote reuse and improve clarity

  • State and control:

    • Variables are used to hold the program’s state, while control structures (like selection and iteration) determine the flow of execution throughout the program

Core programming concepts

Full example

• This script greets the user, asks for two numbers, and multiplies them if they are both greater than 10

• It gives the user three attempts to provide suitable numbers and asks if they want to continue after each attempt

• Finally, it writes the greeting and the last multiplication result to a file

# Constants
MAX_ATTEMPTS = 3
FILENAME = 'output.txt'

# Subroutine to greet a user
def greet(name):
    return "Hello, " + name

# Subroutine to multiply two numbers
def multiply(x, y):
    return x * y

# Main program
def main():
    name = input("Please enter your name: ")
    print(greet(name))

    # Iteration to allow multiple attempts
    for attempt in range(MAX_ATTEMPTS):
        x = int(input("Enter the first number: "))
        y = int(input("Enter the second number: "))

        # Selection
        if x > 10 and y > 10:
            result = multiply(x, y)
            print(f"The product of {x} and {y} is {result}")
        else:
            print("Both numbers should be greater than 10.")
            
        # Asking user if they want to continue
        continue_choice = input("Do you want to continue? (y/n): ")
        if continue_choice.lower() != 'y':
            break

    # File Handling
    with open(FILENAME, 'w') as file:
        file.write(greet(name) + "\n")
        file.write(f"Last multiplication result: {result}")

    print(f"Results have been saved to {FILENAME}")

# Sequence: Calling the main program
if __name__ == "__main__":
    main()