在字符串中交换大小写

Question

我正在尝试解决this challenge in hackerrank，它要求将所有小写字母转换为大写字母，反之亦然。

我尝试使用以下代码：

def swap_case(s):
    length = len(s)
    i=0
    while length:
        if s1[i].isupper():
            s[i].lower()
        elif s[i].islower():
            s[i].upper()
        length-=1
        i+=1
    return s

if __name__ == '__main__':
    s = input()
    result = swap_case(s)
    print(result)

但是返回的字符串与传递给函数的字符串相同。哪里错了？

Answer 1

内置的str.swapcase 已经这样做了。

def swap_case(s):
    return s.swapcase()

Answer 2

正如 cmets 和其他答案中所说，字符串是不可变的。

尝试以下操作：

s = input("Enter input: ")


def convert(ss):
    # Convert it into list and then change it
    newSS = list(ss)
    for i,c in enumerate(newSS):
        newSS[i] = c.upper() if c.islower() else c.lower()
    # Convert list back to string
    return ''.join(newSS)

print(s)
print(convert(s))

# Or use string build in method
print (s.swapcase())

Answer 3

def swap_case(s):
    new = ""
    for i in range(len(s)):
        if str.isupper(s[i]):
            new = new + str.lower(s[i])

        elif str.islower(s[i]):
            new = new + str.upper(s[i])

        else:
            new = new + str(s[i])
        
    return (new)

if __name__ == '__main__':
    s = input()
    result = swap_case(s)
    print(result)

Answer 4

正如@Julien 在评论upper 和lower 中所述，方法返回一个副本，并且不更改对象本身。见this docs。

编辑 @aryamccarthy 让我想起了 Python 中此类任务的现有功能：swapcase() 方法。查看更多here。请注意，这也会返回字符串的副本。

Answer 5

Python-3 内置的 swapcase 函数。

def swap_case(s):
    return s.swapcase()

if __name__ == '__main__':
    s = input()
    result = swap_case(s)
    print(result)

输入：

"Pythonist 3"

输出：

"pYTHONIST 3"

Answer 6

def swap_case(s):
    return s.swapcase()

#or you can use list comprehension 

def swap_case(s):
    new=[ch.lower() if ch.isupper() else ch.upper() for ch in s]
    new=''.join(new)
    return new

if __name__ == '__main__':
    s = input()
    result = swap_case(s)
    print(result)

Answer 7

def swap_case(s):
    l = list(s)
    for i in range(len(s)):
        if l[i].islower():
            l[i] = l[i].upper()
        else:
            l[i] = l[i].lower()
    k = "".join(map(str,l))
    return k

Answer 8

def swap_case(s):
    a=" "
    for i in s:
        if i==i.lower():
            a=a+(i.upper())
        else:
            a=a+(i.lower())
    return (a)

Answer 9

试试这个

def swap_case(s):
    l =[]
    str1 = ''
    for i in s:
        if i.isupper():

            l.append(i.lower())
        elif i.islower():
            l.append(i.upper())
        else:
            l.append(i)
    return (str1.join(l))
if __name__ == '__main__':
    s = input()
    result = swap_case(s)
    print(result)

Answer 10

import string

upalf = string.ascii_uppercase

lowalf = string.ascii_lowercase

def swap_case(s):
    new = ""
    for i in s:
        if i in upalf:
            new += i.lower()
        elif i in lowalf:
            new += i.upper()
        else:
            new += i
    return new

if __name__ == '__main__':
    s = input()
    result = swap_case(s)
    print(result)

**在这个问题中，我使用了一个叫做“string”的模块，里面有属性有大写字母和小写字母**

Answer 11

def swap_case(s):
    list_s= list(s)
    for index,char in enumerate(list_s):
        if char == char.lower():
            list_s[index] =char.upper()
        else:
            list_s[index]= char.lower()
            s = ''.join(list_s)
    return s

string = 'HackerRank.com presents "Pythonist 2".'
print(swap_case(string))