为什么我的 python 代码返回语法错误？

Question

I'm new to python and I've been trying to improve by creating some practice code.

user_number = input('Enter in the number you want the factorial of: ')
print(str(user_number) + '! is equal to ' + str(factorial(int(user_number))))

I've already defined the factorial function earlier in my code and the problem seems to be coming from these two lines. Is there a syntax error which I don't see??

Answer 1

The input function in Python 2 evaluates the user input as Python code rather than taking it literally. You should use raw_input instead in Python 2:

user_number = raw_input('Enter in the number you want the factorial of: ')

Answer 2

Assuming you are using Python 3 since your print statement is a function call. When I tried your code using

import math

then this line instead:

print(str(user_number) + '! is equal to ' + str(math.factorial(int(user_number))))

the result was:

10! is equal to 3628800

I entered a 10 as the value. Perhaps the issue is in your factorial function. Hard to know unless you post that as well.

Answer 3

The below code works for me. I doubt that there may be a problem in your factorial function.

def factorial(n):
    if n == 0:
        return 1
    else:
        return n * factorial(n-1)

user_number = input('Enter in the number you want the factorial of: ')
print(str(user_number) + '! is equal to ' + str(factorial(int(user_number))))