仅读取文件的第一行? [英] Read only the first line of a file?

问题描述

如何用Python仅将文件的第一行作为字符串?

How would you get only the first line of a file as a string with Python?

推荐答案

使用.readline()方法( Python 3文档):

with open('myfile.txt') as f:
    first_line = f.readline()

一些注意事项:

1. 如文档中所述，除非它是文件中的唯一一行，否则从f.readline()返回的字符串将包含尾随换行符.您可能希望使用f.readline().strip()来删除换行符.
2. with语句在块结束时自动再次关闭文件.
3. with语句仅在Python 2.5及更高版本中有效，在Python 2.5中，您需要使用from __future__ import with_statement
4. 在Python 3中，您应该为打开的文件指定文件编码. 了解更多...

1. As noted in the docs, unless it is the only line in the file, the string returned from f.readline() will contain a trailing newline. You may wish to use f.readline().strip() instead to remove the newline.
2. The with statement automatically closes the file again when the block ends.
3. The with statement only works in Python 2.5 and up, and in Python 2.5 you need to use from __future__ import with_statement
4. In Python 3 you should specify the file encoding for the file you open. Read more...

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