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

Posted by john larson
john larson
16,594 Points

In his teachers notes Kenneth says "Just take out the string formatting for that error message"... but how?

The error happens when a non integer is entered into the input field. This code is the teachers code downloaded from Treehouse.

try:
            # get a number guess from the player
            guess = int(input("Guess a number between 1 and 10: "))
        except ValueError:
            print("{} isn't a number!".format(guess))
        else:

this gets printed to the console

Guess a number between 1 and 10: one
Traceback (most recent call last):
  File "C:\Users\smolderingflax\Python Basics\teachers_num_game.py", line 12, in game
    guess = int(input("Guess a number between 1 and 10: "))
ValueError: invalid literal for int() with base 10: 'one'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "C:\Users\smolderingflax\Python Basics\teachers_num_game.py", line 33, in <module>
    game()
  File "C:\Users\smolderingflax\Python Basics\teachers_num_game.py", line 14, in game
    print("{} isn't a number!".format(guess))
UnboundLocalError: local variable 'guess' referenced before assignment

This causes the program to exit instead of the exception being handled and the program continuing

2 Answers

Sabine Maennel
.a{fill-rule:evenodd;}techdegree seal-36
Sabine Maennel
Treehouse Project Reviewer

Hello John,

in your code segment:

try:
            # get a number guess from the player
            guess = int(input("Guess a number between 1 and 10: "))
        except ValueError:
            print("{} isn't a number!".format(guess))
        else:

When you print the error: guess doesn't even exist and you try to use i in your format statement for the error. I don't remember the lesson exactly, but this is what I would do:

# get a number guess from the player
guess = input("Guess a number between 1 and 10: ")
try:
      guess = int(guess)
except ValueError:
     print("{} isn't a number!".format(guess))

When you do it that way: the input statement is save, since you make no assumption, whether it is a number or not. Then the guess = int(guess) statement is unsafe and therefore you put that into a try-except-clause. That way you can react if it fails and now your print statement contains the original guess, which was also safe.

Did this answer help you? With kind regards, Sabine

john larson
john larson
16,594 Points

I think I TRIED to try this approach before but I missed that the input needs to go OUTSIDE the try:

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

Sabine's solution is a bit different from (and possibly better than :+1:) the instructor's suggestion.

:point_right: I believe what Kenneth was suggesting would look something like this:

        try:
            # get a number guess from the player
            guess = int(input("Guess a number between 1 and 10: "))
        except ValueError:
            print("That isn't a number!")
        else:
john larson
john larson
16,594 Points

Hi Steven, leaving out the variable part is one of the suggestions (I think yours actually) I still get the error message with that. The BIG error message not the exception error message that was from the try: except.