How to solve the non-standard file reading error in Python code?

In Python, file reading is a very common operation. However, due to irregularities or sloppiness on the part of the code writer, errors in the way the file is read may result. These errors can cause program crashes, waste time, and even create security risks. This article will introduce how to solve common non-standard file reading errors in Python code.

1. Use absolute paths

In Python, file paths are often used to locate files when reading files. However, using relative paths may cause file reading errors because file paths are calculated relative to the current working directory. The solution to this problem is to use absolute paths. You can use the function os.path.abspath() to get the absolute path of the file, as shown below:

import os
path = os.path.abspath('file.txt')

'file.txt' here represents the file name. This function can ensure that the file is always correctly located and will not cause reading errors due to changes in the file path.

2. Check whether the file exists

Before reading the file, it is best to check whether the file exists to avoid causing program errors if the file does not exist. You can use the function os.path.exists() to check whether the file exists, as shown below:

import os
path = 'file.txt'
if os.path.exists(path):
    with open(path, 'r') as f:
        # 读取文件内容
else:
    print('File does not exist!')

Here path is the file path. If the file exists, open it for reading; otherwise, print an error message.

3. Use the with statement

When using Python to read a file, use the with statement to ensure that the file is closed correctly after use and avoid resource leaks. Inside the with statement, you can perform a series of file operations such as reading and writing, as shown below:

path = 'file.txt'
with open(path, 'r') as f:
    # 读取文件内容

'file.txt' here is the file name, and 'r' means opening the file in read-only mode . At the end of the with statement, the file is automatically closed without manual closing.

4. Use try-except block

During the process of reading a file, the file may encounter problems unexpectedly, such as the file is occupied, the file does not exist, etc. Use a try-except block to avoid these problems and cause the program to crash. Here is an example of a try-except block that reads a file:

path = 'file.txt'
try:
    with open(path, 'r') as f:
        # 读取文件内容
except FileNotFoundError:
    print('File not found!')
except Exception as e:
    print('Error:', e)

This code block can catch FileNotFoundError and other exceptions. If the file cannot be found, the program will output an error message; if it encounters other exceptions, it will also output an error message and record the exception type.

5. Use binary mode

In some cases, you may need to use binary mode when reading files, such as reading binary files such as images and sounds. When using binary mode, you need to use the 'b' identifier in the file opening mode, as shown below:

path = 'image.png'
with open(path, 'rb') as f:
    # 读取二进制文件内容

Here'image.png' is the image file name, and 'rb' means opening in binary mode document. When reading a binary file, you can convert the read content into a byte array for continued processing.

6. Avoid Hardcoding

When writing code, avoiding hardcoding file names and paths can make the code more flexible and maintainable. File paths can be specified using configuration files, command line parameters, etc. to make the code more versatile. The configuration file can contain multiple file paths, and the code can choose one of the paths to read according to the situation to avoid hard-coding problems.

7. Avoid security issues

When reading a file, you may be attacked by malicious code in the file. For example, the files read may contain malicious scripts, viruses, etc. To avoid security issues, appropriate permissions should be used to restrict file reading, writing, and other operations. In addition, you can also use third-party libraries, such as PyPDF2, Pillow, python-docx, etc., to read specific types of files to avoid security risks caused by directly reading files.

Summary

In Python, file reading is a common operation. However, during the file reading process, code writers may make mistakes, resulting in non-standard reading methods, resulting in program crashes, time consuming, and even security risks. To avoid these problems, use absolute paths, check if the file exists, use with statements, use try-except blocks, use binary mode, avoid hardcoding, and avoid security issues. These methods can make the code more standardized, correct, maintainable and safe.

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