使用 Python 访问文件时的差异？

Question

Learning about different access methods that can be used when opening a file with Python. What is the difference between opening a file for both reading and writing vs. opening a file for both writing and reading?

when using the open() function you can use any any of these to open a file:

• r
• r+
• w
• w+
• a
• a+

my question is really would there be a different outcome when using either r+ vs w+ to open files?

Answer 1

The difference between r+ and w+ is that w+ will empty the file first. So you typically use r+ if you want to read the file first, then write to it. You use w+ if you want to write to the file first, then read what you've written.

a+ automatically positions to the end of the file when it's first opened and before every write. So you can use it similarly to r+ , but you have to seek first if you want to read what's already in the file, and all writes are appended to the end.

The modes without + just allow reading or writing, not both.