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Python Python Basics (2015) Number Game App Number Game Refinement

Posted by Tamas Gonda
Tamas Gonda
7,332 Points

except ValueError doesn't seems to work fine!

Hello Dear friends! I've done what Dave said. used try and then except finished off with an else. The program seems working fine, as it's throws the message that it's not a number, if I type anything else, BUT: it prints the last typed number instead of the letter. So for example I type 3 = try again, 6 = try again, H = 6 is not a number! if the first try is a letter, it gives me an error message: During handling of the above exception, another exception occurred:

Traceback (most recent call last):
File "number_game.py", line 17, in <module>
game()
File "number_game.py", line 9, in game
print("{} is not a number!".format(guess))
UnboundLocalError: local variable 'guess' referenced before assignment

while len(guesses) < 5:
        try:
            guess = int(input("Try guess my number!"))
        except ValueError:
            print("{} is not a number!".format(guess))
        else:

3 Answers

Steven Parker
Steven Parker
231,271 Points
Steven Parker
Steven Parker
231,271 Points

The variable guess is only assigned when the int conversion is successful, so when the exception occurs, it still contains the last valid guess. Of course, if the very first input causes the exception, it has not been assigned yet at all.

You can resolve this by using separate steps for getting the input and converting it to a number:

    while len(guesses) < 5:
        answer = input("Try to guess my number!")
        try:
            guess = int(answer)
        except ValueError:
            print("{} is not a number!".format(answer))
Tamas Gonda
Tamas Gonda
7,332 Points

Thank you so much! It was bothering me a lot! So just simply have to declare the variable earlier, and that holds the value, whatever it is.

Vanessa Van Gilder
Vanessa Van Gilder
7,034 Points

Is there a reason you made a new variable called answer? I did this and just kept it as guess.

Steven Parker
Steven Parker
231,271 Points
Steven Parker
Steven Parker
231,271 Points

I made "answer" represent what was given by the user, and kept "guess" to represent a successfully converted number value.

hamsternation
hamsternation
26,616 Points
hamsternation
hamsternation
26,616 Points

Hey actually, if you see the teacher's note, that is an error in the code.

Just throw out the .format part of the code and don't use the {} and you should be fine.

Teacher's Note:

Did you catch the possible problem where we take a user's guess during the game? Since we convert their input()'d guess into an int right away, if they give us something that can't be turned into a number, it'll throw a ValueError. So far, so good, 'cause that's what our try is for, right?

Except in the except ValueError: we used the guess variable, which will be undefined and throw it's own new error. Oh no! Just take out the string formatting for that error message, though, and you should be good to go.

Steven Parker
Steven Parker
231,271 Points
Steven Parker
Steven Parker
231,271 Points

That would fix the issue, but it gives up repeating the bad input in the error message. The solution I suggested resolves the issue and keeps that feature.

Tamas Gonda
Tamas Gonda
7,332 Points

Yeah, I totally missed that! My bad! Thank you!

Jonathan Ankiewicz
Jonathan Ankiewicz
17,901 Points
Jonathan Ankiewicz
Jonathan Ankiewicz
17,901 Points

if your running it locally you may need to change input to raw_input