Answer to Question #246583 in Python for Raymond Ekwubiri

Question

Exercise 8.4 from your textbook. Each of the following Python functions is supposed to check whether its argument has any lowercase letters.

For each function, describe what it actually does when called with a string argument. If it does not correctly check for lowercase letters, give an example argument that produces incorrect results, and describe why the result is incorrect.

# 1

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


# 2

def any_lowercase2(s):
for c in s:
if 'c'.islower():
return 'True'
else:
return 'False'


# 3

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


# 4

def any_lowercase4(s):
flag = False
for c in s:
flag = flag or c.islower()
return flag

Answer 1

# 1
def any_lowercase1(s):
    """Actually returns True whether _first_ letter is lowercase otherwise False

    Incorrect result: argument has three lowercase 'z' - expected True
    >>> any_lowercase1('Bzzz')
    False
    """
    for c in s:
        if c.islower():
            return True
        else:
            return False

# 2
def any_lowercase2(s):
    """Actually _always_ retuns _string_ "True"

    Incorrect result: argument has no lowercase letters - expected False
    >>> any_lowercase2('UEFA')
    'True'
    """
    for c in s:
        if 'c'.islower():
            return 'True'
        else:
            return 'False'

# 3
def any_lowercase3(s):
    """Actually returns True whether _last_ letter is lowercase otherwise False

    Incorrect result: argument has four lowercase 'd' - expected True
    >>> any_lowercase3('ddddD')
    False
    """
    for c in s:
        flag = c.islower()
    return flag

# 4
def any_lowercase4(s):
    """Actually returns True whether _any_ letter is lowercase otherwise False
        No incorrect results

    Argument has lowercase 'x' - expected True
    >>> any_lowercase4('Ux')
    True

    Argument nas no lowercase letters - expected False
    >>> any_lowercase4('BAR')
    False
    """
    flag = False
    for c in s:
        flag = flag or c.islower()
    return flag

# 5
def any_lowercase5(s):
    """Actually returns True whether _all_ letters is lowercase otherwise False

    Incorrect result: all letters in argument except 'E' are lowercase - expected True
    >>> any_lowercase5('abcdEfg')
    False
    """
    for c in s:
        if not c.islower():
            return False
    return True

if __name__ == '__main__':
    import doctest
    doctest.testmod(verbose=True)