Python中遇到的问题

4、 网站要求用户输入用户名和密码进行注册。编写程序以检查用户输入的密码的有效性。若不符合要求，则给出提示，提醒密码不满足哪个条件；若符合要求，则提示注册成功。
以下是检查密码的标准：
l [a-z]之间至少有1个字母
l [0-9]之间至少有1个数字
l [A-Z]之间至少有一个字母
l [$＃@]中至少有1个字符
l 最短交易密码长度：6
l 交易密码的最大长度：12

def main():
    # Prompt the user to enter a password
    password = input("Enter a password: ")

    # Check the password against the standards
    has_lowercase = False
    has_uppercase = False
    has_digit = False
    has_special = False
    length = len(password)

    for c in password:
        if c.islower():
            has_lowercase = True
        elif c.isupper():
            has_uppercase = True
        elif c.isdigit():
            has_digit = True
        elif c in ['$', '#', '@']:
            has_special = True

    # Print a message based on the password's validity
    if not has_lowercase:
        print("The password must contain at least one lowercase letter.")
    elif not has_uppercase:
        print("The password must contain at least one uppercase letter.")
    elif not has_digit:
        print("The password must contain at least one digit.")
    elif not has_special:
        print("The password must contain at least one special character ($, #, or @).")
    elif length < 6:
        print("The password must be at least 6 characters long.")
    elif length > 12:
        print("The password must be no more than 12 characters long.")
    else:
        print("The password is valid.")

if __name__ == '__main__':
    main()