The file is to store some storage, so that it can be used directly the next time the program is executed without having to make a new copy, saving time and effort.
2. How to open the file?
Python has a built-in open() method that can read and write files.
Using the open() method to operate a file is like stuffing an elephant into the refrigerator. It can be divided into three steps, one is to open the file, the other is to operate the file, and the third is to close the file.
open syntax
The return value of the open() method is a file object, which can be assigned to a variable (file handle).
The basic syntax format is:
f = open(filename, mode)
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Note:
In Python , all objects with read and write methods can be classified as file types. All file type objects can be opened using the open method and ended with the close method.
filename: A string value containing the name of the file you want to access, usually a file path.
mode: There are many modes for opening files. The default is read-only mode r.
in 1 Python is a very good language for writing .txt files. Python.
3. Access mode
Through a table, learn about the commonly used reading and writing modes of Python
Access Mode
Description
r
##Open the file read-only. The file pointer will be placed at the beginning of the file. (default mode).
##w
##Open a file for writing only enter. If the file already exists, it is overwritten. If the file does not exist, create a new file.
##a
##Open a file for appending. If the file already exists, the file pointer will be placed at the end of the file. In other words, new content will be written after existing content. If the file does not exist, create a new file for writing.
##rb
To open a file in binary format use Read only. The file pointer will be placed at the beginning of the file. This is the default mode.
##wb
##Open a file in binary format only for writing. If the file already exists, it is overwritten. If the file does not exist, create a new file.
##ab
##To open a file in binary format use In addition. If the file already exists, the file pointer will be placed at the end of the file. In other words, new content will be written after existing content. If the file does not exist, create a new file for writing.
r
Open a file for reading and writing . The file pointer will be placed at the beginning of the file.
w
Open a file for reading and writing . If the file already exists, it is overwritten.If the file does not exist, create a new file.
a
Open a file for reading and writing . If the file already exists, the file pointer will be placed at the end of the file. The file will be opened in append mode. If the file does not exist, a new file is created for reading and writing.
##rb
To open a file in binary format use To read and write. The file pointer will be placed at the beginning of the file.
wb
To open a file in binary format use To read and write. If the file already exists, it is overwritten. If the file does not exist, create a new file.
ab
To open a file in binary format use In addition. If the file already exists, the file pointer will be placed at the end of the file. If the file does not exist, a new file is created for reading and writing.
如果要读取非UTF-8编码的文件，需要给open()函数传入encoding参数。
例如，读取GBK编码的文件：
>>> f = open('gbk.txt', 'r', encoding='gbk')
>>> f.read()
'GBK' #编码
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