python - 将文本和行添加到文件的开头 (Python)

Question

关于相关问题，我想知道如何在 Python 中将文本和/或行添加到文件的开头，因为有人建议这是一种更简单的文本/文件操作语言。因此，当我问之前的 C++ 链接问题时，谁能告诉我如何使用 Python 完成此操作？

引用链接(相关)问题:

I'd like to be able to add lines to the beginning of a file.

This program I am writing will take information from a user, and prep it to write to a file. That file, then, will be a diff that was already generated, and what is being added to the beginning is descriptors and tags that make it compatible with Debian's DEP3 Patch tagging system.

有人有任何建议或代码吗？

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Related: Adding text and lines to the beginning of a file (C++)

Answer 1

最近有很多类似的文件I/O问题..

简而言之，您需要创建一个新文件

1. 首先，向文件写入新行
2. 从旧文件中读取行并将它们写入文件

如果您可以保证添加到开头的每一行新行都比开头对应的每一行长，您可以就地完成:

f = open('file.txt','r+')
lines = f.readlines() # read old content
f.seek(0) # go back to the beginning of the file
f.write(new_content) # write new content at the beginning
for line in lines: # write old content after new
    f.write(line)
f.close()

上面的示例在找到文件开头的位置后将所有数据完整写入，因为文件内容已被新内容覆盖。

否则您需要写入一个新文件

f = open('file.txt','r')
newf = open('newfile.txt','w')
lines = f.readlines() # read old content
newf.write(new_content) # write new content at the beginning
for line in lines: # write old content after new
    newf.write(line)
newf.close()
f.close()