How to deal with file reading and writing problems in Python

How to handle file reading and writing in Python requires specific code examples

In Python, file reading and writing is a common operation task. Whether processing text files or binary files, Python provides powerful and flexible file reading and writing functions. This article will introduce how to handle file reading and writing in Python and give specific code examples.

1. File reading operation

1. Open the file

In Python, use the open() function to open the file. The open() function accepts two parameters: file name and open mode. There are many options for opening modes, the commonly used ones are:

• 'r': read-only mode, only reading operations can be performed after opening the file.
• 'w': Write mode, if the file exists, clear the file content; if the file does not exist, create a new file.
• 'a': append mode, if the file exists, append to the end of the file; if the file does not exist, create a new file.

Sample code:

file = open("file.txt", "r")

2. Read file content

There are many ways to read file content, the most common is to use The read() method can be used to read the entire file content at once, or the readline() method can be used to read the file content line by line.

Sample code (read the entire file content at once):

content = file.read()

Sample code (read the file content line by line):

line = file.readline()
while line:
    print(line)
    line = file.readline()

3. Close the file

After reading the file, be sure to remember to close the file. Closing a file frees system resources and ensures that the file is saved and consistent.

Sample code:

file.close()

2. File write operation

1. Open file

Similar to file read operation, use open( ) function to open the file. But when opening a file, you need to specify the opening mode as 'w' or 'a'.

Sample code (write mode):

file = open("file.txt", "w")

2. Write file content

There are many ways to write file content, the most common Use the write() method to write string content. You can also use the writelines() method to write multiple lines of content.

Sample code (write single line content):

file.write("Hello, World!")

Sample code (write multiple lines content):

lines = ["Line 1
", "Line 2
", "Line 3
"]
file.writelines(lines)

3. Close the file

After writing the file, be sure to remember to close the file. Closing a file frees up system resources and ensures that the file is saved and consistent.

Sample code:

file.close()

3. Exception handling

During the file reading and writing process, some abnormal situations may occur, such as the file does not exist, file permissions are insufficient, etc. In order to ensure the stability of the program, you can use the try-except statement to catch and handle these exceptions.

Sample code:

try:
    file = open("file.txt", "r")
    # 文件读取操作
except FileNotFoundError:
    print("文件不存在！")
except PermissionError:
    print("权限不足！")
finally:
    file.close()

4. Summary

Through the introduction of this article, we have learned how to handle file reading and writing in Python. Use the open() function to open the file and select the appropriate opening mode when needed. When reading a file, you can read the entire file at once or read the file line by line. When writing to a file, you can use the write() method to write string content or the writelines() method to write multi-line content. Finally, don't forget to close the file and use exception handling mechanisms to catch and handle exceptions. I hope this article will help you deal with file reading and writing problems in Python!

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