How to Fix a Blackjack Game in Python

I recently had the opportunity to help a client debug and enhance their Blackjack game written in Python. What started off as a simple script evolved into a great learning opportunity not just in solving errors, but in thinking through code structure, edge cases, and gameplay logic. In this post, I’ll walk through the key error that was breaking the script, explain how I fixed it, and share how I enhanced the code for a better gameplay experience.

The Main Error Identified

The Error Message:

: Can't convert 'int' object to str implicitly

What Went Wrong:

This issue popped up in the function responsible for generating the deck of cards:

for rank in ['A', 2, 3, 4, 5, 6, 7, 8, 9, 10, 'J', 'Q', 'K']:
    deck.append(suit + rank)

Here, the code attempts to concatenate a string (suit, like "H") with an integer (rank, like 2), which Python doesn’t allow. Unlike some other languages, Python is strict about type conversions.

The Fix:

The solution was simple and clean: I wrapped the rank variable with str() so all elements in the deck are strings:

deck.append(suit + str(rank))

This allowed the suit and rank to merge correctly into card strings like "H2" or "SK".

Other Issues Discover

Another bug appeared later in the script:

hands = playingHands(dck)

Here, dck was undefined. It was a typo. The correct variable name should have been mydeck:

hands = playingHands(mydeck)

Once these errors were corrected, I could run the game smoothly but I didn’t stop there.

Final Working Blackjack Game

I decided to rebuild the structure with better variable naming, improved logic for scoring Aces, and an intuitive player loop. Here’s the cleaned-up and functional version of the game:

import random

def deck():
    cards = []
    for suit in ['H','S','D','C']:
        for rank in ['A',2,3,4,5,6,7,8,9,10,'J','Q','K']:
            cards.append(suit + str(rank))  # FIXED
    random.shuffle(cards)
    return cards

def pCount(cards):
    count = 0
    aceCount = 0
    for card in cards:
        rank = card[1:]  # Extract rank
        if rank in ['J', 'Q', 'K', '10']:
            count += 10
        elif rank == 'A':
            aceCount += 1
        else:
            count += int(rank)

    # Handle Aces logic
    if aceCount > 0:
        if count + 11 + (aceCount - 1) <= 21:
            count += 11 + (aceCount - 1)
        else:
            count += aceCount
    return count

def playingHands(deck):
    dealerhand = [deck.pop(), deck.pop()]
    playerhand = [deck.pop(), deck.pop()]
    return dealerhand, playerhand

# Main Game Loop
game = ""
mydeck = deck()
dealer, player = playingHands(mydeck)

while game.lower() != 'exit':
    dealerCount = pCount(dealer)
    playerCount = pCount(player)

    print("\nDealer's Hand:", dealer)
    print("Player's Hand:", player)
    print("Player total:", playerCount)

    if playerCount == 21:
        print("Blackjack! Player wins!")
        break
    elif playerCount > 21:
        print(f"Player busts with {playerCount} points. Dealer wins!")
        break
    elif dealerCount > 21:
        print(f"Dealer busts with {dealerCount} points. Player wins!")
        break

    game = input("What would you like to do? H: hit, S: stand, Exit: exit > ").upper()

    if game == 'H':
        player.append(mydeck.pop())
    elif game == 'S':
        while pCount(dealer) < 17:
            dealer.append(mydeck.pop())

        dealerCount = pCount(dealer)
        playerCount = pCount(player)
        print("\nFinal Hands:")
        print("Dealer's Hand:", dealer, "| Total:", dealerCount)
        print("Player's Hand:", player, "| Total:", playerCount)

        if playerCount > 21:
            print("Player busts. Dealer wins!")
        elif dealerCount > 21:
            print("Dealer busts. Player wins!")
        elif playerCount > dealerCount:
            print("Player wins!")
        elif playerCount < dealerCount:
            print("Dealer wins!")
        else:
            print("It's a tie!")
        break

Features I’d Like to Add Next

To make this a more complete experience for players, I’ve brainstormed several enhancements that would be exciting for future iterations:

• Replay Option: Allow players to play multiple rounds in one session.
• Betting System: Add a virtual currency and bets to make the game more engaging.
• Split Hand / Double Down: Introduce more advanced Blackjack rules.
• Card Display Enhancements: Replace strings like "HA" with visual symbols like "♥A".
• Dealer Hidden Card: Reveal one card at the beginning, and the second only after the player stands.

Final Thoughts

Debugging this Blackjack game was a satisfying mix of problem-solving and creativity. The initial issues stemmed from simple type mismatches and variable naming errors things that can easily slip through when writing quick scripts. Once those were out of the way, it opened the door to improve the gameplay, organize the logic, and consider new features for a more robust player experience.