python一次读1000个，直到文件结束？ [英] python read 1000 at a time until end of file?

问题描述

我一直在做一个python项目，把信息发送给服务器，当我发现一些很好的代码来读取文件并发送时，我只能一次发送整个文件。我希望能够一次读取1000个字符，并循环直到文件结束。我相信这很容易，但我不知道要改变我为了做到这一点而改变了什么。这也可能是由于对阅读方法不熟悉，但是我正在研究它，没有找到任何为我澄清的信息。这就是我正在使用的：

  with open（localFileTT，'rb'，0）as f：#open the （fstr）
 print（fstr）
 fstr中的'str'：
 break 
  

我还没有在这个代码中引入网络功能，因为它只是测试材料，弄清楚如何只读1000时间。它当然能够读取整个部分，但我不知道如何改变它，以便一次只读取部分内容。我会尝试加入阅读（1000），但打印空虚！我不确定阅读是在哪里发生的，不幸的是，迄今为止在线阅读的这些代码的部分文章（例如，）没有任何帮助。如果有人能指出我的方向，那么我会很感激。

解决方案

file.read（） 需要大小 em>参数：
$ b

从文件中读取至多 size 字节 size 字节）。如果 size 参数为负值或省略，则读取所有数据，直到到达EOF。

您可以在循环中使用它，并结合 iter（）函数（将第二个参数设置为作为标记）和 functools.partial（） 的效率：

 从functools导入部分
 
打开（localFileTT，'rb'，0）作为f：
 （部分（f.read，1000），''）：
＃chunk长达1000个字符
  

另一种方法是在循环中使用：



 打开（localFileTT，'rb'，0）作为f：
而真：
 chunk = f.read（1000）
如果不是大块：
＃已到达EOF ，结束循环
 bre ak 
＃chunk长达1000个字符
  

如果您已经试过读取（1000）并得到一个空字符串，当时您的文件已经在EOF。

I've been working on a python project to send information to a server, and while I found some nice code to read the file and send it, I can only send the entire thing at once. I want instead to be able to read 1000 characters at a time, and loop until the file's end. I'm sure that this is pretty easy, but I'm not sure where to change what I've been doing to make it happen. This might also be due to unfamiliarity with the method of reading, but I am researching it and not finding any information that has clarified it for me. This is what I'm working with:

with open(localFileTT, 'rb', 0) as f: #open the file 
    for fstr in f:
        str.encode(fstr)
        print(fstr)
        if 'str' in fstr:
            break

I have not yet introduced network functions in this code, as it is only test material to figure out how to read only 1000 at a time. It certainly reads the entire section well enough, but I don't know how to change it so as to read only parts at a time. I would try just adding read(1000) but that prints emptiness! I'm not sure where exactly the reading is occurring here, and unfortunately the articles I've read online thus far on parts of this code (such as with) has not helped any. If anyone can point me in the right direction, then I will be quite grateful.

解决方案

file.read() takes a size argument:

Read at most size bytes from the file (less if the read hits EOF before obtaining size bytes). If the size argument is negative or omitted, read all data until EOF is reached.

You can use that in a loop, combined with the iter() function (with the second argument set to '' as a sentinel), and functools.partial() for efficiency:

from functools import partial

with open(localFileTT, 'rb', 0) as f:
    for chunk in iter(partial(f.read, 1000), ''):
        # chunk is up to 1000 characters long

The alternative would be to use a while loop:

with open(localFileTT, 'rb', 0) as f:
    while True:
        chunk = f.read(1000)
        if not chunk:
            # EOF reached, end loop
            break
        # chunk is up to 1000 characters long

If you already tried read(1000) and got an empty string back, your file was already at EOF at the time.

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