Troubleshooting a Roulette Game Program in Python

Click For Summary
SUMMARY

The forum discussion focuses on troubleshooting an UnboundLocalError in a Python Roulette game program. The error arises when the variable 'col' is referenced before being assigned a value, particularly when the user chooses 'No' in response to the play prompt. A solution is proposed to initialize 'col' with a default value, or to exit the function early when 'No' is selected, preventing the error from occurring. The discussion emphasizes the importance of ensuring all code paths return a value to avoid similar issues.

PREREQUISITES
  • Understanding of Python programming syntax
  • Familiarity with function definitions and variable scope in Python
  • Knowledge of handling user input in Python
  • Basic understanding of error handling in Python
NEXT STEPS
  • Learn about Python variable scope and the implications of local vs global variables
  • Research Python error handling techniques, specifically using try-except blocks
  • Explore best practices for function design in Python, including return values
  • Study how to implement user input validation in Python programs
USEFUL FOR

Beginner Python programmers, game developers looking to implement user interaction, and anyone interested in debugging Python code effectively.

azerty12
Messages
15
Reaction score
0
Hi guys
I'm trying to program a Roulette game on Python
My programs asks for inputs and I gave names to these inputs.
The point is, since I didn't assign these names before, the following error occurs:
UnboundLocalError: local variable 'color' referenced before assignment

I tried to get rid of this error with exceptions, but I couldn't
Any idea?
 
Technology news on Phys.org
Could you paste your code here? Perhaps it's a problem of local/global variables? Do you refer to a variable which is defined inside a function?
 
radou said:
Could you paste your code here? Perhaps it's a problem of local/global variables? Do you refer to a variable which is defined inside a function?

Hi Radou
Here's my program (edited with IDLE)
The problem occurs when I execute Roulette() on python's shell and when I choose 'No' when he asks me whether I want to play

I didn't put much comments on my program, so if there is something you don't understand, just ask.

Since I can't attach the file with IDLE, I'm gone send it to you on notepad
 

Attachments

In your Game function, when the user responds with "No", the col variable is uninitialized.

Code:
def Game(bet,result):
    if result==51:
        print("first attempt")  
    else:
        print("You had to choose:",result)       
    print("You have:",bet,"$")
    if bet==0:
        return "plucked"
    play=input("do you want to play? Yes/No")
    if play=='No':
        print("Wise decision","you leave with",bet,"$")
    elif play=='Yes':
        gamble=input("What number do you choose?")
        gamble=int(gamble) #Number you bet on
        col=color(gamble)
    result=randrange(50)
    
    if result==gamble:
        return Game(3*bet,result)
    elif color(result)==col:
        return Game(ceil(0.5*bet),result)
    elif gamble>50:
        print("wrong choice")
    else:    
        return Game(0,result)

I believe that your problem occurs when the code tries to execute elif color(result) == col.

If this is the problem, you could fix it by assigning a value to col like this:
Code:
def Game(bet,result):
    col = 'Black'
    if result==51:
        print("first attempt")  
    else:
        print("You had to choose:",result)       
    print("You have:",bet,"$")
    if bet==0:
        return "plucked"
    play=input("do you want to play? Yes/No")
    if play=='No':
        print("Wise decision","you leave with",bet,"$")
    elif play=='Yes':
        gamble=input("What number do you choose?")
        gamble=int(gamble) #Number you bet on
        col=color(gamble)
    result=randrange(50)
    
    if result==gamble:
        return Game(3*bet,result)
    elif color(result)==col:
        return Game(ceil(0.5*bet),result)
    elif gamble>50:
        print("wrong choice")
    else:    
        return Game(0,result)
Another way that's probably better is to exit the function if the user enters "No".
 
I'm afraid the first way doesn't work, it generates the following exception:
UnboundLocalError: local variable 'col' referenced before assignment

About your second suggestion: Could you tell me how to exit the function please? (I just begging in programming)
 
azerty12 said:
I'm afraid the first way doesn't work, it generates the following exception:
UnboundLocalError: local variable 'col' referenced before assignment
I didn't test the code I wrote, but I think it should work. Did you notice the line I added to your code?
Code:
def Game(bet,result):
    col = 'Black' <=== added

azerty12 said:
About your second suggestion: Could you tell me how to exit the function please? (I just begging in programming)
Just return some appropriate value. BTW, there are several code paths in your Game function that don't return anything. Each of the if ... elif branches ought to return something.
 
Mark44 said:
I didn't test the code I wrote, but I think it should work. Did you notice the line I added to your code?
Code:
def Game(bet,result):
    col = 'Black' <=== added
Yes I did notice the line you added. But it still raises the same kind of exception.


Mark44 said:
Just return some appropriate value. BTW, there are several code paths in your Game function that don't return anything. Each of the if ... elif branches ought to return something.

Do you mean that instead of printing things like "wrong number"... I should return these?
 
azerty12 said:
Yes I did notice the line you added. But it still raises the same kind of exception.
See if this makes a difference.
Code:
if play=='No':
        print("Wise decision","you leave with",bet,"$")
        return

As you have described things, you're getting the error when you type "No". In that case, col doesn't get set, but there is code below that executes, that tries to compare col with color(result).

I think that's what's causing your error.
azerty12 said:
Do you mean that instead of printing things like "wrong number"... I should return these?
 
You have quite a few variables that are referenced when they may not be defined. Mark44's suggestion should take care of the problem.
 
  • #10
Mark44 said:
See if this makes a difference.
Code:
if play=='No':
        print("Wise decision","you leave with",bet,"$")
        return

As you have described things, you're getting the error when you type "No". In that case, col doesn't get set, but there is code below that executes, that tries to compare col with color(result).

I think that's what's causing your error.

Absolutely Mark, you got it!

Thanks a lot and thanks to jihae and radou
 

Similar threads

  • · Replies 17 ·
Replies
17
Views
2K
Replies
55
Views
7K
Replies
11
Views
4K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 21 ·
Replies
21
Views
3K
  • · Replies 15 ·
Replies
15
Views
2K
Replies
3
Views
1K
  • · Replies 3 ·
Replies
3
Views
2K
  • · Replies 17 ·
Replies
17
Views
3K
  • · Replies 3 ·
Replies
3
Views
2K