读文件的正确方法及其背后机制

应该使用以下格式读文件：

with open(...) as f:
for line in f:
<do something with line>

其理由如下：

The [code]with

statement handles opening and closing the file, including if an exception is raised in the inner block. [/code]

The [code]for line in f

treats the file object

f

as an iterable, which automatically uses buffered IO and memory management[/code]

so you don't have to worry about large files.