IndexError：字符串索引超出范圍 2018 python 3

Question

這段代碼基本上反映了您輸入的字符串。 我正進入（狀態

Type something please: Hey Hello                                                                                                                                                        
Traceback (most recent call last):                                                                                                                                                      
  File "Week3Basic1.py", line 13, in <module>                                                                                                                                           
    mirror(input("Type something please: "))                                                                                                                                            
  File "Week3Basic1.py", line 9, in mirror                                                                                                                                              
    result = last+  mirror(middle) + first                                                                                                                                              
  File "Week3Basic1.py", line 9, in mirror                                                                                                                                              
    result = last+  mirror(middle) + first                                                                                                                                              
  File "Week3Basic1.py", line 9, in mirror                                                                                                                                              
    result = last+  mirror(middle) + first                                                                                                                                              
  File "Week3Basic1.py", line 4, in mirror                                                                                                                                              
    first= string[0]                                                                                                                                                                    
IndexError: string index out of range  

代碼：

def mirror(string):

      first= string[0]
      middle= string[1:-2]
      last= string[-1]


      result = last+  mirror(middle) + first

      print (result)

    mirror(input("Type something please: "))

Answer 1

為了正常工作，您的函數假定輸入的長度至少為兩個字符。

同時，它在輸入的縮短版本上遞歸地調用自己——你需要考慮這個遞歸調用鏈何時以及如何停止。

您需要考慮的這一方面稱為基本情況。