如果 boolean function 调用的条件在 Python 中始终为 True

Question

I have written a program and at the end I have written a code for the user to rate my program, but it has some issues please help:

while True:
    RR = input("What would you rate this program(?/5): ")
    if RR.isnumeric:
        rating = int(RR)
        if rating >= 5:
            print("Looks like you are highly satisfied with this program :D")
            break
        elif rating == 4 or rating == 3:
            print("Ohh! Next time I'll try my best to change this '",rating,"' into 5 ;D")
            break
        elif rating == 1 or rating == 2:
            print("I am sorry if I wasn't good, I'll try my best next time :|")
            break
    else:
        print("Invalid Rating, Try again...")
        continue

Result

What would you rate this program(?/5): g
ValueError: invalid literal for int() with base 10: 'g'

What I want is that if someone enters a text instead of a number then it tells that it's an invalid input and continues the loop. How can I get this?

Answer 1

Your if condition is not a function call, but rather a reference to the function. It is not yet called.

It should be if RR.isnumeric() not if RR.isnumeric .

Answer 2

Your code has two problems.

1. Your if condition checks str(RR).isnumeric which is always True, since that function exists for all string objects. Change it to RR.isnumeric() .

2. In your inner if you might want to put in an else:contine to not bypass the voting system, when a value smaller than 1 is entered.

Here's code that should do what you want:

while True:
    RR = input("What would you rate this program(?/5): ")
    if RR.isnumeric():
        rating = int(RR)
        if rating >= 5:
            print("Looks like you are highly satisfied with this program :D")
            break
        elif rating in [3, 4]:
            print("Ohh! Next time I'll try my best to change this '",rating,"' into 5 ;D")
            break
        elif rating in [1, 2]:
            print("I am sorry if I wasn't good, I'll try my best next time :|")
            break
        else:
            print("Invalid Rating, Try again...\nPlease enter a value from 1 to 5")
    else:
        print("Invalid Rating, Try again...\nPlease enter a value from 1 to 5")

You should tell the user what they should do imo, and you don't need a continue in a while True if you don't need to skip any code anyway. Also a list comparison to check if your rating is within a set of numbers is nicer to read. Another very enjoyable way to compare ranges in Python is like this:

if 0 < x < 7:
    pass
elif 6 < x < 10:
    pass

But for small ranges like in your case, I prefer using lists.

HTH