在python中，如何检查字符串是否同时包含大写和小写字母

Question

我查看了与我的问题Password check- Python 3 类似的另一篇文章，除了我的问题涉及检查密码是否同时包含大写和小写问题。我的代码如下，但执行时无法识别密码中的大小写字母，它只能识别一种类型。我如何让它识别这两种类型？还有一种更简单的方法可以让代码检查是否所有这些值都发生了，而不必为每个单独的步骤创建函数？

def Get_Password():
    return input("Enter your desired password: ")

def Count_Digits(password):
    return sum(character.isdigit() for character in password)

def Valid_password_length(password):
    if len(password) >= 10:
        return ('step1' == True)
    else:
        return ('step1' == False, print("Invalid password: too short"))

def Valid_password_characters(password):
    if password.isalnum():
        return ('step2' == True)
    else:
        return ('step2' == False, print("Invalid password: illegal character detected"))

def Valid_password_numdigit(password):
    if Count_Digits(password) >= 2:
        return ('step3' == True)
    else:
        return ('step3' == False, print("Invalid password: Must have at least 2 digits"))

def Valid_password_lowercase(password):
    for i in (password):
        if i.islower() == True:
            return ('step4' == True)
        else:
            return ('step4' == False, print("Invalid password: No lowercase characters detected"))

def Valid_password_uppercase(password):
    for i in (password):
        if i.isupper() == True:
            return ('step5' == True)
        else:
            return ('step5' == False, print("Invalid password: No uppercase characters detected"))

def password_checker():
    password = Get_Password()
    Valid_password_length(password)
    Valid_password_characters(password)
    Valid_password_numdigit(password)
    Valid_password_lowercase(password)
    Valid_password_uppercase(password)

    if 'step1' and 'step2' and 'step3' and 'step4' and 'step5' == True:
        print("Congratulations! This password is valid")

password_checker()

Answer 1

import sys

def Valid_password_mixed_case(password):
    letters = set(password)
    mixed = any(letter.islower() for letter in letters) and any(letter.isupper() for letter in letters)
    if not mixed:
        print("Invalid password: Mixed case characters not detected", file=sys.stderr)
    return mixed

一个完整的解决方案：

import sys

def Get_Password():
    return input("Enter your desired password: ")

def Count_Digits(password):
    return sum(1 for character in password if character.isdigit())

def Valid_password_length(password):
    correct_length = len(password) >= 10

    if not correct_length:
        print("Invalid password: too short", file=sys.stderr)

    return correct_length

def Valid_password_characters(password):
    correct_characters = password.isalnum()

    if not correct_characters:
        print("Invalid password: illegal character detected", file=sys.stderr)

    return correct_characters

def Valid_password_numdigit(password):
    sufficient_digits = Count_Digits(password) >= 2

    if not sufficient_digits:
        print("Invalid password: Must have at least 2 digits", file=sys.stderr)

    return sufficient_digits

def Valid_password_mixed_case(password):
    letters = set(password)

    lower = any(letter.islower() for letter in letters)
    upper = any(letter.isupper() for letter in letters)

    if not upper:
        print("Invalid password: No uppercase characters detected", file=sys.stderr)

    if not lower:
        print("Invalid password: No lowercase characters detected", file=sys.stderr)

    return lower and upper

def password_checker():
    password = Get_Password()
    if Valid_password_length(password) and \
        Valid_password_characters(password) and \
        Valid_password_numdigit(password) and \
        Valid_password_mixed_case(password):

        print("Congratulations! This password is valid")

password_checker()

Answer 2

您的问题很容易回答。您正在返回 return('steps' == True) 形式的东西，它总是会返回 false。因此，只需将它们替换为 return True 或 return False。

假设您修复了上述问题，您的循环也是错误的。您只想在遍历整个字符串后返回 false。考虑密码：ABCd。这包含一个小写字符，但您的 check lowercase 方法将返回 false，因为第一个字母是大写的。您想查看密码中的每个字符，如果这些字符都不是小写，则返回 false。

如果您想要一种更简洁的方式，cdlane's answer 是一种不错的 Python 方式。

Answer 3

回答标记为重复的问题Break line not executing：

password = input('Enter your password')
password_letters = list(password)
upper = False
lower = False
name = 'Papa'
surname = 'Johns'

for letter in password_letters:
    if letter.isupper():
        upper = True
    elif letter.islower():
        lower = True

    if upper and lower:
        break

if len(password) <= 5:
    print('password is to short')
elif name.lower() in password.lower() or surname.lower() in password.lower():
    print('You cannot have first or last name in password')
elif not (upper and lower):
    print('You must have both upper and lower case in password')
else:
    print('Password is valid')

Answer 4

你可以使用正则表达式：

即：

def Valid_mixed_password(password):
    lower = re.compile(r'.*[a-z]+') # Compile to match lowercase
    upper = re.compile(r'.*[A-Z]+') # Compile to match uppercase
    if lower.match(password) and upper.match(password): # if the password contains both (lowercase and uppercase letters) then return True
        return True
    else: # Else, the password does not contains uppercase and lowercase letters then return False
        return False

>>> print Valid_mixed_password("hello")
False
>>> print Valid_mixed_password("HELLO")
False
>>> print Valid_mixed_password("HellO")
True
>>> print Valid_mixed_password("heLLo")
True

希望对您有所帮助。