In [1]:

    

def reverse(s):
    len=0
    sub_s=''
    for ch in s:
        len+=1
    for i in range(len,0,-1):
        print(sub_s[i])
        
        
#原函数
reverse('abcde')


    

    




---------------------------------------------------------------------------
IndexError                                Traceback (most recent call last)
<ipython-input-1-d825570d3803> in <module>()
      9 
     10 #原函数
---> 11 reverse('abcde')
     12 

<ipython-input-1-d825570d3803> in reverse(s)
      5         len+=1
      6     for i in range(len,0,-1):
----> 7         print(sub_s[i])
      8 
      9 

IndexError: string index out of range

In [2]:

    

def my_len(line)：
    for i in range(1, len(line)*2):
        if i == 1:
            print(line[0])
        elif i%2 == 1:
            print(line[:i//2] + line[i//2] + line[i//2-1::-1])
        else:
            print(line[:i//2] + line[i//2-1::-1])
            
#原函数
my_len('今夜偏知春气暖')


    

    




  File "<ipython-input-2-ee80441ab6b1>", line 1
    def my_len(line)：
                    ^
SyntaxError: invalid character in identifier

In [ ]:

    

def change(word)
    len = 0
    sub_word = ''
    for ch in word
        len+=1
    if word[len]==y