python - 索引错误: list index out of range error when reversing a list

Question

这个问题已经有答案了:

Does "IndexError: list index out of range" when trying to access the N'th item mean that my list has less than N items? (7 个回答)

已关闭 4 年前。

当我输入以下内容时:

def FirstReverse(str): 

 # code goes here

x = len(str)

s = list(str)

while x >= 0:
 print s[x]
 x = x - 1

# keep this function call here  
# to see how to enter arguments in Python scroll down
print FirstReverse(raw_input())

我收到此错误

ERROR ::--Traceback (most recent call last):
File "/tmp/105472245/main.py", line 14, in <module>
print FirstReverse("Argument goes here")
File "/tmp/105472245/main.py", line 7, in FirstReverse
print s[x] IndexError: list index out of range

Answer 1

Python 索引从 0 开始。因此，对于字符串“Hello”，索引 0 指向“H”，索引 4 指向“o”。当你这样做时:

x = len(str)

您将 x 设置为 5，而不是最大索引 4。因此，请尝试以下操作:

x = len(str) - 1

另外，还有另一个指针。而不是:

x = x - 1

您可以简单地说:

x -= 1