1.使用字串切片

>>> def reverse1():
...     s = input("please input a string: ")
...     return s[::-1]
... 
>>> reverse1()
please input a string: yangyue!
'!euygnay'

2.使用遞迴

>>> def reverse2(s):
...     if s == "":
...             return s
...     else:
...             return reverse2(s[1:]) + s[0]
... 
>>> s = 'yangxinyue'
>>> reverse2(s)
'euynixgnay'
 

3.使用列表的reverse

>>> def reverse3(s):
...     l = list(s)
...     l.reverse()
...     print("".join(l))
... 
>>> reverse3('yangxinyue')
euynixgnay