使用readline读取txt文件python3
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Use readline to read txt file python3
提问by Code971
I been working on this for hours and I cant get it right, any help would be appreciated! My question is how do I use the function .readline()to read until the end of a text file? I know that .readlines()work as well but I'm trying to process one line at a time.
我已经为此工作了几个小时，但我无法做到正确，任何帮助将不胜感激！我的问题是如何使用该函数.readline()读取到文本文件的末尾？我也知道这.readlines()行得通，但我正在尝试一次处理一行。
Here's what I have for my code so far:
到目前为止，这是我的代码：
a = open("SampleTxt.txt","r")
While True:
a.readline()
My problem is that I get an infinite loop when I run this, shouldn't it have stopped once it couldn't read a line any more?
我的问题是当我运行这个时我得到了一个无限循环，一旦它不能再读取一行，它不应该停止吗？
回答by Jon Clements
a.readline()will return ''an empty string when no more data is available, you need to check that and then break your while, eg:
a.readline()''当没有更多数据可用时将返回一个空字符串，您需要检查它然后打破你的while，例如：
while True:
line = a.readline()
if not line:
break
If it's not purely for learning purposes then you really should be using a withstatement and for-loop to process the file, line by line:
如果不是纯粹出于学习目的，那么您确实应该使用with语句和 for 循环来逐行处理文件：
with open('SampleTxt.txt') as fin:
for line in fin:
pass # do something
It's more clear as to your intent, and by using the withblock, the fileobj will be released on an exception or when the block ends.
你的意图更清楚，通过使用with块，fileobj 将在异常或块结束时被释放。
