Python回车不起作用 [英] Python carriage return not working

问题描述

我有一个长时间运行的脚本，它在数据库中的行上循环.我经常希望它打印它处理了多少行，但每次都不要创建一个新行.这基本上就是我所拥有的:

I have a long-running script that loops over rows in a database. Every so often I'd like it to print how many rows it's processed, but without creating a new line each time. This is essentially what I have:

import sys
mystr = "{} rows complete\r"

for i in range(0, 100):
    if i % 10 == 0:
        sys.stdout.write(mystr.format(i))
        sys.stdout.flush()

当我运行它时(在 Python 2.7.5 64 位，Windows 上)我得到:

When I run this (on Python 2.7.5 64-bit, Windows) I get:

0 rows complete
10 rows complete
20 rows complete
...
100 rows complete

谁能想到为什么回车不起作用?我在这里看到了一些关于 Python 和 \r 的类似问题，但所有的答案都说包括我拥有的 sys.stdout.flush().

Can anyone think of why the carriage return isn't working? I've seen some similar questions here about Python and \r, but all the answers say to include sys.stdout.flush(), which I have.

推荐答案

使用 \r 可能是正确的方法，但行为在很大程度上取决于文本的输出方式.并非所有终端都会尊重回车:

Using \r is probably the correct way to go here, but the behaviour depends very much on how the text is being output. Not all terminals will respect a bare carriage return:

cmd.exe 和 powershell.exe 都应该以您期望的方式输出文本(Powershell ISE 没有，但这是一个红鲱鱼).

cmd.exe and powershell.exe should both output the text the way you expect (Powershell ISE doesn't but that's a red herring here).

Python 自己的 idle 将忽略回车，所有输出都在一行中.

Python's own idle will ignore the carriage return, all output comes on one long line.

正如您所指出的，您自己的编辑器的命令窗口也会忽略 \r.

As you noted, your own editor's command window also ignores \r.

此外，如果您从交互式窗口尝试，您还会在每一行的末尾得到一些数字输出:那是因为交互式窗口有助于输出对 sys.stdout.flush() 调用的结果代码>.

Also, if you try from an interactive window you also get some numbers output at the end of each line: that's because the interactive windows helpfully outputs the result of the call to sys.stdout.flush().

这篇关于Python回车不起作用的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！