Given this solution to Exercise 9, modify it to have one level of user feedback: if the user does not enter a number between 1 and 9, tell them. Don’t count this guess against the user when counting the number of guesses they used.
import random
number = random.randint(1, 9)
number_of_guesses = 0
while True:
guess = int(input("Guess a number between 1 and 9: "))
number_of_guesses += 1
if guess == number:
break
print(f"You needed {number_of_guesses} guesses to guess the number {number}")Using the terminology from the discussion in the exercise, the exercise is asking to implement one logical error handling (i.e. making sure the guess is between the numbers 1 and 9) and one Pythonic error handling (making sure the input is strictly a number).
So the solution combines the two techniques discussed.
Firstly, we need to implement an “inner loop” to make sure we have a loop set up to ask the user over and over again for a guess. This is the default - we always ask the user, and only “break” out of the loop when the user’s input meets all of our criteria. The logical error check is implemented with an if statement: if the guess is between the numbers 1 and 9, we break out of the inner loop. The Pythonic error check is implemented using a try / catch statement. Combining these two cases is subtle: we put the logical check inside the try clause of the Pythonic check - this is if statement will then only get executed if the previous line (the line with the int(input())) does not throw a ValueError. This is a very “Pythonic” way of implemeting the solution to this problem - rather than having two separate checks one after the other, we take advantage of the properties of try / catch blocks to do both for us!
Check it out:
import random
number = random.randint(1, 9)
number_of_guesses = 0
while True:
while True:
try:
guess = int(input("Guess a number between 1 and 9: "))
if guess >= 1 and guess <= 9:
break
else:
print("Your input must be a number between 1 and 9 inclusive")
except ValueError:
print("You must enter a number")
number_of_guesses += 1
if guess == number:
break
print(f"You needed {number_of_guesses} guesses to guess the number {number}")