Codehs 4.7 11 Rock Paper Scissors

Let's delve into creating a Rock Paper Scissors game using CodeHS, specifically addressing the challenges presented in exercise 4.7.11. This seemingly simple game provides an excellent opportunity to solidify your understanding of fundamental programming concepts, including user input, conditional statements, random number generation, and function design. We'll not just provide the code, but also explain the logic and reasoning behind each step.

Breaking Down Rock Paper Scissors: A Coding Perspective

The core of Rock Paper Scissors lies in comparing choices. The user selects one of three options (rock, paper, or scissors), and the computer randomly selects its own. The program then determines the winner based on these well-defined rules:

• Rock beats Scissors
• Scissors beats Paper
• Paper beats Rock
• If both players choose the same option, it's a tie.

Translating these rules into code requires careful use of conditional statements (if, elif, else) to handle each possible scenario. We'll also need functions to encapsulate specific parts of the game, making the code more organized and readable.

Step-by-Step Guide: Building the Game in CodeHS

We will start with a basic structure and gradually add complexity to improve functionality and user experience.

1. Setting Up the Basic Structure

First, let's establish the fundamental structure of our CodeHS program. This involves including necessary libraries and defining the main function.

import random

def main():
    """
    This function runs the Rock Paper Scissors game.
    """
    print("Welcome to Rock Paper Scissors!")
    play_game()

def play_game():
    """
    Handles the main game logic.
    """
    user_choice = get_user_choice()
    computer_choice = get_computer_choice()
    print("You chose: " + user_choice)
    print("The computer chose: " + computer_choice)
    determine_winner(user_choice, computer_choice)

# Add other function definitions (get_user_choice, get_computer_choice, determine_winner) here

if __name__ == "__main__":
    main()

In this snippet, we import the random module, which we'll need later for the computer's choice. The main function serves as the entry point of our program, printing a welcome message and calling the play_game function. The play_game function is responsible for orchestrating the core game logic, obtaining the user's and computer's choices, and then determining the winner. Note the use of docstrings ("""...""") to explain what each function does – this is good programming practice.

2. Getting User Input

Now, let's implement the get_user_choice function. This function prompts the user to enter their choice (rock, paper, or scissors) and validates the input to ensure it is one of the allowed options.

def get_user_choice():
    """
    Gets the user's choice and validates it.
    """
    while True:
        choice = input("Choose rock, paper, or scissors: ").lower()
        if choice in ["rock", "paper", "scissors"]:
            return choice
        else:
            print("Invalid choice. Please choose rock, paper, or scissors.")

This function uses a while True loop to continuously prompt the user until a valid choice is entered. The .lower() method converts the input to lowercase to make the comparison case-insensitive. If the input is valid (i.e., it's in the list ["rock", "paper", "scissors"]), the function returns the choice. Otherwise, it prints an error message and the loop continues. This error handling is crucial for making the game user-friendly.

3. Generating the Computer's Choice

Next, we need a function to generate the computer's choice randomly. This is where the random module comes in.

def get_computer_choice():
    """
    Generates the computer's choice randomly.
    """
    choices = ["rock", "paper", "scissors"]
    return random.choice(choices)

The get_computer_choice function creates a list of possible choices and then uses random.choice(choices) to select a random element from that list. This ensures the computer's choice is unpredictable and fair.

4. Determining the Winner

The most complex part of the game is determining the winner. We need to implement the rules of Rock Paper Scissors using conditional statements.

def determine_winner(user_choice, computer_choice):
    """
    Determines the winner based on the user's and computer's choices.
    """
    if user_choice == computer_choice:
        print("It's a tie!")
    elif (user_choice == "rock" and computer_choice == "scissors") or \
         (user_choice == "scissors" and computer_choice == "paper") or \
         (user_choice == "paper" and computer_choice == "rock"):
        print("You win!")
    else:
        print("The computer wins!")

This function uses a series of if, elif, and else statements to cover all possible outcomes. The first if statement checks for a tie. The elif statement checks all the winning scenarios for the user, using the or operator to combine multiple conditions. If neither of these conditions is met, the else statement concludes that the computer wins. The backslash \ is used to break up the long conditional statement into multiple lines for better readability.

5. Putting It All Together

Now, let's combine all the functions into a complete, runnable program:

import random

def main():
    """
    This function runs the Rock Paper Scissors game.
    """
    print("Welcome to Rock Paper Scissors!")
    play_game()

def play_game():
    """
    Handles the main game logic.
    """
    user_choice = get_user_choice()
    computer_choice = get_computer_choice()
    print("You chose: " + user_choice)
    print("The computer chose: " + computer_choice)
    determine_winner(user_choice, computer_choice)

def get_user_choice():
    """
    Gets the user's choice and validates it.
    """
    while True:
        choice = input("Choose rock, paper, or scissors: ").lower()
        if choice in ["rock", "paper", "scissors"]:
            return choice
        else:
            print("Invalid choice. Please choose rock, paper, or scissors.")

def get_computer_choice():
    """
    Generates the computer's choice randomly.
    """
    choices = ["rock", "paper", "scissors"]
    return random.choice(choices)

def determine_winner(user_choice, computer_choice):
    """
    Determines the winner based on the user's and computer's choices.
    """
    if user_choice == computer_choice:
        print("It's a tie!")
    elif (user_choice == "rock" and computer_choice == "scissors") or \
         (user_choice == "scissors" and computer_choice == "paper") or \
         (user_choice == "paper" and computer_choice == "rock"):
        print("You win!")
    else:
        print("The computer wins!")

if __name__ == "__main__":
    main()

This code provides a fully functional Rock Paper Scissors game. You can copy and paste this code into CodeHS and run it.

Enhancements and Further Development

While the code above provides a solid foundation, there are several ways to enhance the game and add more features.

1. Adding Score Tracking

Let's add score tracking to keep track of the user's and computer's wins.

import random

def main():
    """
    This function runs the Rock Paper Scissors game with score tracking.
    """
    print("Welcome to Rock Paper Scissors!")
    user_score = 0
    computer_score = 0
    while True:  # Play multiple rounds
        result = play_game()
        if result == "user":
            user_score += 1
            print("You win this round!")
        elif result == "computer":
            computer_score += 1
            print("The computer wins this round!")
        else:
            print("It's a tie this round!")

        print("Score - You: " + str(user_score) + ", Computer: " + str(computer_score))

        play_again = input("Play again? (yes/no): ").lower()
        if play_again != "yes":
            break

    print("Final Score - You: " + str(user_score) + ", Computer: " + str(computer_score))
    if user_score > computer_score:
        print("Congratulations! You won the game!")
    elif computer_score > user_score:
        print("The computer won the game!")
    else:
        print("The game ended in a tie!")



def play_game():
    """
    Handles the main game logic and returns the winner.
    """
    user_choice = get_user_choice()
    computer_choice = get_computer_choice()
    print("You chose: " + user_choice)
    print("The computer chose: " + computer_choice)
    return determine_winner(user_choice, computer_choice)  # Return the winner

def get_user_choice():
    """
    Gets the user's choice and validates it.
    """
    while True:
        choice = input("Choose rock, paper, or scissors: ").lower()
        if choice in ["rock", "paper", "scissors"]:
            return choice
        else:
            print("Invalid choice. Please choose rock, paper, or scissors.")

def get_computer_choice():
    """
    Generates the computer's choice randomly.
    """
    choices = ["rock", "paper", "scissors"]
    return random.choice(choices)

def determine_winner(user_choice, computer_choice):
    """
    Determines the winner based on the user's and computer's choices.
    Returns "user", "computer", or "tie".
    """
    if user_choice == computer_choice:
        print("It's a tie!")
        return "tie"
    elif (user_choice == "rock" and computer_choice == "scissors") or \
         (user_choice == "scissors" and computer_choice == "paper") or \
         (user_choice == "paper" and computer_choice == "rock"):
        print("You win!")
        return "user"
    else:
        print("The computer wins!")
        return "computer"

if __name__ == "__main__":
    main()

Key changes include:

• Score Variables: We initialize user_score and computer_score to 0.
• Game Loop: A while True loop allows the game to be played multiple times.
• play_again Input: The user is asked if they want to play again after each round.
• determine_winner Return Value: The determine_winner function now returns "user", "computer", or "tie" to indicate the outcome.
• Score Updates: The main function updates the scores based on the result of each round.
• Final Score: The final score is printed, and the overall winner is declared.

2. Input Validation with More Robust Error Handling

We can further improve input validation by handling potential errors like the user entering a number or special characters.

def get_user_choice():
    """
    Gets the user's choice and validates it with robust error handling.
    """
    while True:
        try:
            choice = input("Choose rock, paper, or scissors: ").lower()
            if choice in ["rock", "paper", "scissors"]:
                return choice
            else:
                print("Invalid choice. Please choose rock, paper, or scissors.")
        except:
            print("Invalid input. Please enter text only.")

The try...except block handles potential exceptions that might occur if the user enters something unexpected. This makes the game more resilient to invalid input.

3. Adding a Graphical User Interface (GUI)

For a more engaging experience, you could consider adding a GUI using a library like Tkinter or Pygame (though the latter might be beyond the scope of a typical CodeHS exercise). A GUI would allow users to click buttons for their choices instead of typing them in.

4. Implementing Different Difficulty Levels

You could introduce different difficulty levels by modifying the computer's strategy. For example, at a higher difficulty, the computer could analyze the user's past choices and try to predict their next move. This would involve storing the user's choices in a list and using some simple pattern recognition.

5. Using Enums for Choices

Instead of using strings directly for the choices, you can use an enum (enumeration) to make the code more readable and maintainable. While CodeHS might not fully support enums in the most sophisticated way, you can simulate their behavior using a dictionary or a simple class.

class Choice:
    ROCK = "rock"
    PAPER = "paper"
    SCISSORS = "scissors"

def get_user_choice():
    """
    Gets the user's choice using Choice enum.
    """
    while True:
        choice = input("Choose rock, paper, or scissors: ").lower()
        if choice in [Choice.ROCK, Choice.PAPER, Choice.SCISSORS]:
            return choice
        else:
            print("Invalid choice. Please choose rock, paper, or scissors.")

def get_computer_choice():
    """
    Generates the computer's choice using Choice enum.
    """
    choices = [Choice.ROCK, Choice.PAPER, Choice.SCISSORS]
    return random.choice(choices)

def determine_winner(user_choice, computer_choice):
    """
    Determines the winner using Choice enum.
    """
    if user_choice == computer_choice:
        print("It's a tie!")
        return "tie"
    elif (user_choice == Choice.ROCK and computer_choice == Choice.SCISSORS) or \
         (user_choice == Choice.SCISSORS and computer_choice == Choice.PAPER) or \
         (user_choice == Choice.PAPER and computer_choice == Choice.ROCK):
        print("You win!")
        return "user"
    else:
        print("The computer wins!")
        return "computer"

This makes it easier to change the choice options later without having to search and replace strings throughout your code.

Common Mistakes and How to Avoid Them

• Case Sensitivity: Remember to convert user input to lowercase using .lower() to avoid issues with capitalization.
• Incorrect Logic: Double-check your conditional statements to ensure they accurately reflect the rules of Rock Paper Scissors. A truth table can be helpful for visualizing all the possible outcomes.
• Missing return Statements: Ensure your functions return the expected values. For example, get_user_choice should return the user's choice, and determine_winner should return a value indicating the winner.
• Infinite Loops: Be careful with while loops. Make sure there's a condition that will eventually cause the loop to terminate. In the get_user_choice function, the loop terminates when the user enters a valid choice.
• Unclear Error Messages: Provide informative error messages to guide the user when they make a mistake.

Conclusion

Building a Rock Paper Scissors game in CodeHS is a valuable exercise that reinforces fundamental programming concepts. By breaking down the problem into smaller, manageable functions, you can create a well-organized and easy-to-understand program. Remember to test your code thoroughly and consider adding enhancements to make the game more engaging and user-friendly. This seemingly simple game provides a solid foundation for tackling more complex programming challenges in the future. Don't be afraid to experiment and explore different approaches to solving the problem. The key is to keep practicing and refining your skills.