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Question

下面我用islower（）制作了5个不同的函数。目标是检查给定函数是否满足目的，即检查给定字符串是否包含至少一个小写。我也附上了理由，请检查我的分析/解释是否有效。

#Example1: True
def any_lowercase1(s):
     for c in s:
          if c.islower():
               return True
          else:
               return False

#Example2: False
## this function checks only the string 'c' is lower, which always returns True
def any_lowercase2(s):
     for c in s:
          if 'c'.islower():
               return 'True'
          else:
               return 'False'

#Example3: False
##the result only depends on the last letter of given string

def any_lowercase3(s):
     for c in s:
          flag = c.islower()
     return flag

#Example4: False
##Similar to Example3, this function also depends on the last character of given string
def any_lowercase4(s):
     flag = False
     for c in s:
          flag = flag or c.islower()
     return c.islower()


#Example5: False
## This function returns False if it conatains more than one Captial Letter.
def any_lowercase5(s):
     for c in s:
          if not c.islower():
               return False
     return True

print(any_lowercase4('RrR'))
#above must be true, but it returns False

Answer 1

我会使用正则表达式：

>>> import re
>>> re.findall('[a-z]', 'RrR')
['r']
>>> re.findall('[a-z]', 'RRR')
[]

示例4不起作用，因为当您应该返回c.islower()时返回flag。

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如果你需要检查哪个功能有效，哪个不行 - 用一些已知数据写一些测试：

if __name__ == '__main__':
    ONLY_LOWER = ['aaa', 'a', 'hello', 'foo and bar']
    NOT_LOWER = ['X', 'Xa', 'Aha', 'Try this One']
    FUNCS = [any_lowercase1, any_lowercase2, any_lowercase3, any_lowercase4, any_lowercase5]


    good_funcs = [f.__name__ for f in FUNCS]
    for f in FUNCS:
        result = True
        for item in ONLY_LOWER:
            if not f(item):
                print("Function '<{}>' returned false for lower item '{}'".format(f.__name__, item))
                if f.__name__ in good_funcs:
                    good_funcs.remove(f.__name__)
                break
        for item in NOT_LOWER:
            if f(item):
                print("Function '<{}>' returned true for non lower item '{}'".format(f.__name__, item))
                if f.__name__ in good_funcs:
                    good_funcs.remove(f.__name__)
                break

    print("Here are function, which passed the tests: {}".format(good_funcs))

>> Function '<any_lowercase2>' returned true for non lower item 'X'
>> Function '<any_lowercase3>' returned true for non lower item 'Xa'
>> Function '<any_lowercase4>' returned true for non lower item 'Xa'
>> Function '<any_lowercase5>' returned false for lower item 'foo and bar'
>> Here are function, which passed the tests: ['any_lowercase1']

（验证）Python中不同类型的islower（）方法

1 个答案:

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