Python 中“虽然不是 EOF"的完美对应物是什么?

2022-01-24 00:00:00 python file iteration eof

问题描述

要在 C 或 Pascal 中读取一些文本文件，我总是使用以下代码段来读取数据，直到 EOF:

To read some text file, in C or Pascal, I always use the following snippets to read the data until EOF:

while not eof do begin
  readline(a);
  do_something;
end;

因此，我想知道如何在 Python 中简单快速地做到这一点?

Thus, I wonder how can I do this simple and fast in Python?

解决方案

遍历文件读取行:

with open('somefile') as openfileobject:
    for line in openfileobject:
        do_something()

文件对象是可迭代的，并且在 EOF 之前产生行.将文件对象用作可迭代对象使用缓冲区来确保高性能读取.

File objects are iterable and yield lines until EOF. Using the file object as an iterable uses a buffer to ensure performant reads.

你可以对标准输入做同样的事情(不需要使用 raw_input():

You can do the same with the stdin (no need to use raw_input():

import sys

for line in sys.stdin:
    do_something()

为了完成图片，可以通过以下方式完成二进制读取:

To complete the picture, binary reads can be done with:

from functools import partial

with open('somefile', 'rb') as openfileobject:
    for chunk in iter(partial(openfileobject.read, 1024), b''):
        do_something()

其中 chunk 将包含来自文件的最多 1024 个字节，并且当 openfileobject.read(1024) 开始返回空字节字符串时迭代停止.

where chunk will contain up to 1024 bytes at a time from the file, and iteration stops when openfileobject.read(1024) starts returning empty byte strings.

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