[英]Index out of range in python while reading multiple lines from a file
我对python中的索引感到困惑。 我正在使用以下代码从文件中读取一行并打印列表中的第一项。 我认为每次读取一行索引都会设置为零。 我的以下代码索引超出范围。 请说明我要去哪里。
fname = input("Enter file name: ")
fh = open(fname)
for line in fh:
line = line.strip()
print(line)
b = line.split()
print(b[0])
如果字符串为空,可能会变坏。
In [1]: line = ' '
In [2]: line = line.strip()
In [4]: b = line.split()
In [5]: b
Out[5]: []
In [6]: b[0]
---------------------------------------------------------------------------
IndexError Traceback (most recent call last)
<ipython-input-6-422167f1cdee> in <module>()
----> 1 b[0]
IndexError: list index out of range
也许如下更新您的代码:
fname = input("Enter file name: ")
fh = open(fname)
for line in fh:
line = line.strip()
b = line.split()
if b:
print(b[0])
如果line
为空白(换句话说,它仅由空格和回车组成),则在line.strip()
之后将为空字符串。
>>> line = ""
>>> line.split()[0]
Traceback (most recent call last):
File "<pyshell#50>", line 1, in <module>
line.split()[0]
IndexError: list index out of range
换句话说,当对空字符串使用split
,将返回一个空列表。 因此不存在零元素。
如前所述,如果行为空白,则会出现索引错误。
如果您想阅读行,也许只需更改一些代码即可让Python为您完成工作
fname = input("Enter file name: ")
with open(fname) as f
lines = f.readlines()
# f will be closed at end of With statement no need to take care
for line in lines:
line = line.strip()
print(line)
# following line may not be used, as line is a String, just access as an array
#b = line.split()
print(line[0])
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