Python Core Programming - Protective Code

1. Protective programming

Protective programming is a method of writing code with the goal of minimizing the errors and vulnerabilities that may occur in the code. Here are some suggestions for writing protective code:

1. Input validation: All external input, such as user input, network data, etc., must be verified and filtered to prevent errors caused by malicious input or invalid data.
2. Exception handling: Use try-except statements in your code to catch possible exceptions and handle them appropriately to avoid program crashes or unpredictable behavior.
3. Data type checking: Use appropriate data types such as integers, strings, lists, etc. in your code and perform type checking to avoid type conversion errors or other type-related issues.
4. Null value checking: Use appropriate null value checking like None or NULL in your code to avoid null pointer references or other null value related issues.
5. Logging: Add appropriate logging to your code to make it easier to troubleshoot errors or exceptions when they occur.
6. Write clear documentation: Add appropriate comments and documentation to your code so that other developers can more easily understand and maintain it.
7. Use the latest security measures: Keep your code base updated to use the latest security measures to protect your code from the latest vulnerabilities.
8. Conduct testing: Conduct proper testing before and after writing the code to ensure its correctness and reliability.
   In summary, writing protective code requires comprehensive consideration of many aspects, including input validation, exception handling, type checking, null checking, logging, documentation, security measures, and testing.

2. Input verification

Validating input is an important step in protective programming to ensure that your program does not cause errors or vulnerabilities due to malicious or invalid input.

def get_user_input():
    try:
        user_input = input("Please enter a number: ") # 获取用户输入
        user_input = int(user_input) # 将用户输入转换为整数
        if user_input < 0: # 如果用户输入的数小于0，则抛出异常
            raise ValueError("Number must be greater than or equal to 0")
        return user_input # 返回用户输入
    except ValueError as e:
        print("Invalid input:", e) # 如果出现异常，输出错误信息
        return None # 返回空值
user_input = get_user_input() # 调用函数获取用户输