如何确保输入符合要求

Question

用户必须输入密码，但密码中必须至少包含1个大写，小写和数字。

password = input("Please enter a password: ")

Answer 1

if any(x.isupper() for x in password) and \ 
   any(x.islower() for x in password) and \
   any(x.isdigit() for x in password):
    print ("Congratulations, you have a secure password.")

Answer 2

你也可以放入一个在这些条件匹配之前不会停止的while循环：

while True:
     password = input("Please enter a password: ")
     if any(x.isupper() for x in password) and \ 
        any(x.islower() for x in password) and \
        any(x.isdigit() for x in password): #copy from Rob's awnser
            break

     else: print('Invalid!')