Python exception handling: master the sharp edge and control your code life

python is a powerful programming language, but it is not perfect. When running a Python program, you may encounter various exceptions, causing the program to crash or produce erroneous results. In order to avoid these situations from happening, we need to handle abnormal situations, that is, exception handling.

The basic syntax for exception handling is try-except-finally. The try statement block contains code that may cause an exception, the except statement block is used to catch exceptions, and the finally statement block is used for code that will be executed regardless of whether an exception occurs. .

The following is a simple exception handling example:

try:
# 可能引发异常的代码
except Exception as e:
# 捕获异常并处理
finally:
# 无论是否发生异常，都会执行的代码

In the above example, the code in the try statement block that may cause an exception is the divide-by-zero operation. When a division-by-zero operation occurs, a ZeroDivisionError exception is raised, which is caught by the except statement block, and the code in the except statement block is executed. finally The code in the statement block will be executed regardless of whether an exception occurs.

In Python, we can use the r<strong class="keylink">ai</strong>se keyword to actively raise exceptions. raise The keyword can be followed by an exception class or exception object. For example, we can use the following code to actively raise the ValueError exception:

raise ValueError("参数错误")

When we actively raise an exception, the program will immediately stop running and throw an exception. We can use the try-except statement block to capture actively raised exceptions and handle them.

In addition to the built-in exception classes, we can also customize exception classes. The syntax of a custom exception class is as follows:

class 自定义异常类名(Exception):
# 异常类的代码

In the above example, we defined an exception class named Custom exception class name, which inherits from the Exception class. We can use the following code to throw a custom exception:

raise 自定义异常类名("自定义异常消息")

When we throw a custom exception, the program will immediately stop running and throw an exception. We can use the try-except statement block to catch custom exceptions and handle them.

Exception handling is a very important concept in Python. Mastering the skills of exception handling can help us control our code life and avoid troubles caused by various unexpected situations.

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