readlines() 在 Python 3 中是否返回列表或迭代器?

2022-01-10 00:00:00 python python-3.x iterator readlines

问题描述

我读过深入 Python 3".那:

I've read in "Dive into Python 3" that:

readlines() 方法现在返回一个迭代器，因此它与 Python 2 中的 xreadlines() 一样高效".em>

"The readlines() method now returns an iterator, so it is just as efficient as xreadlines() was in Python 2".

参见:附录 A:移植代码使用 2to3 到 Python 3:A.26 xreadlines() I/O 方法.

我不确定这是不是真的，因为他们在这里没有提到:http://docs.python.org/release/3.0.1/whatsnew/3.0.html .如何检查?

I'm not sure that's true because they don't mention it here: http://docs.python.org/release/3.0.1/whatsnew/3.0.html . How can I check that?

解决方案

像这样:

Python 3.1.2 (r312:79149, Mar 21 2010, 00:41:52) [MSC v.1500 32 bit (Intel)] on win32 Type "help", "copyright", "credits" or "license" for more information. >>> f = open('/junk/so/foo.txt') >>> type(f.readlines()) <class 'list'> >>> help(f.readlines) Help on built-in function readlines: readlines(...) Return a list of lines from the stream. hint can be specified to control the number of lines read: no more lines will be read if the total size (in bytes/characters) of all lines so far exceeds hint. >>>

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