python--file Operations

The open function , which is used for file processing

When working with files, you typically need to go through the following steps:

• Open File
• Manipulating files

First, open the file

1	文件句柄 =open(‘文件路径‘, ‘模式‘)

When you open a file, you need to specify the file path and how you want to open the file, and then open it to get the file handle and manipulate it later through the file handle.

The mode of opening the file is:

• R, read-only mode "default"
• W, write-only mode "unreadable; not exist" created; empty content;
• X, write-only mode "unreadable; not present, create, present error"
• A, append mode "readable; not present, create; append content only;"

"+" means you can read and write a file at the same time

• r+, read and write "readable, writable"
• w+, write "readable, writable"
• x+, write "readable, writable"
• A +, write "readable, writable"

"B" means to operate in bytes

• RB or R+b
• WB or W+b
• XB or W+b
• AB or A+b

Note: When opened in B, the content read is byte type, and the byte type is also required for writing

Second, the operation

Python2 Python3

Iii. Management Context

To avoid forgetting to close a file after opening it, you can manage the context by:

123	with open(‘log‘,‘r‘) as f:           ...

This way, when the with code block finishes executing, the internal automatically shuts down and frees the file resource.

In Python 2.7 and later, with also supports the management of multiple file contexts simultaneously, namely:

12	with open(‘log1‘) as obj1,open(‘log2‘) as obj2:    pass

python--file Operations