Python_报错：SyntaxError: 'break' outside loopIndexError: list assignment index out of range

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今天发现一个报错，卡了好几个点，后来发现原因后，脸上三条黑线，尴尬啊！！！

报错：SyntaxError: ‘break‘ outside loopIndexError: list assignment index out of range

上源码：

def func(n,target_str):
with open("1003.txt","r+",encoding="utf-8") as fp:
word_str = fp.read()
print(word_str)
if n < len(word_str):
word_list = word_str.split()
word_list[n] = target_str
print(word_list)
else:
print("111")

调用该方法传入参数 func(2,"111")

报错了：

>>> func(2,"111")
gg111ggggggg222
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "<stdin>", line 7, in func
IndexError: list assignment index out of range

>>> def func(n,target_str):
...     with open("1003.txt","r+",encoding="utf-8") as fp:
...         word_str = fp.read()
...         print(word_str)
...         if n < len(word_str):
...             word_list = word_str.split()#这里不能这么写啊，详见如下说明
...             word_list[n] = target_str
...             print(word_list)
...         else:
...             print("111")
...
>>>
>>> func(2,"111")
gg111ggggggg222
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 7, in func
IndexError: list assignment index out of range
>>>

因为我源文件"1003.txt"的内容是：gg111ggggggg222

如果按上面的split()写法转成列表就会认作一个整体,结果会是[‘gg111ggggggg222‘]，不是我要的结果

   这里的 word_str的值是：gg111ggggggg222

word_list = word_str.split()#这里不能这么写

改成如下就好了：

word_list = list(word_str)#会将所有元素单独赋值给列表

精简下，就是如下意思：
str1 = "qwer"
list1 = str1.split()
list2 = list(str1)

print(list1)
print(list2)

>>> str1 = "qwer"
>>> list1 = str1.split()#该场景下会作为整体转换为列表
>>> list2 = list(str1)#该场景下会将单个元素赋值给列表
>>>
>>>
>>> print(list1)
[‘qwer‘]
>>> print(list2)
[‘q‘, ‘w‘, ‘e‘, ‘r‘]
>>> 

可参照：Python_列表和字符串间的转换  简单说明

Python_报错：SyntaxError: 'break' outside loopIndexError: list assignment index out of range

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原文地址：https://www.cnblogs.com/rychh/p/9740798.html