Exception handling techniques in Python

In Python programming, when an error or exception occurs during code execution, the program will stop execution. In order to allow the program to continue executing when an exception occurs, Python provides an exception handling mechanism. This article will introduce readers to exception handling techniques in Python.

1. try-except statement

In Python, you can use the try-except statement to handle exceptions. Its basic format is as follows:

try:
    # 可能会出现异常的代码
except Exception as e:
    # 如果出现异常，执行这里的代码

In this try-except statement, the code that may cause exceptions needs to be placed in the try code block. If an exception occurs in the code in the try code block, it will jump to the except code block for execution instead of directly terminating the program.

It should be noted that Exception in the except statement is a general exception type. If you want to handle only specific types of exceptions, you can replace Exception with a specific exception type. For example:

try:
    a = 10 / 0
except ZeroDivisionError as e:
    print('除数不能为0。')

In this code, we specify that we only handle exceptions like ZeroDivisionError. If other types of exceptions occur in the try code block, the program will crash directly.

2. try-except-else statement

In addition to the try-except statement, Python also provides the try-except-else statement. Its basic format is as follows:

try:
    # 可能会出现异常的代码
except Exception as e:
    # 如果出现异常，执行这里的代码
else:
    # 如果没有出现异常，执行这里的代码

In this statement, the code in the else code block will only be executed when there is no exception in the code in the try code block. This statement is very useful when processing certain operations that require subsequent operations based on the results of code execution.

3. try-except-finally statement

In addition to the try-except-else statement, Python also provides the try-except-finally statement. Its basic format is as follows:

try:
    # 可能会出现异常的代码
except Exception as e:
    # 如果出现异常，执行这里的代码
finally:
    # 无论有没有出现异常，都会执行这里的代码

In this statement, the code in the finally code block will be executed regardless of whether an exception occurs in the code in the try code block. This statement is very useful when cleaning work is required, such as closing files, closing database connections, etc.

4. Throw exceptions

In Python, you can also use the raise statement to manually throw exceptions. Its basic format is as follows:

raise Exception('错误信息')

In this statement, we manually threw an Exception and passed in an error message. This statement is useful when you need to manually detect certain situations and throw exceptions.

5. Customized exceptions

In addition to using the exception types that come with Python, you can also customize exception types. Its basic format is as follows:

class CustomException(Exception):
    pass

In this code, we define an exception type named CustomException and let it inherit from Exception. In actual programming, we can customize different exception types as needed to make the code more readable and maintainable.

Summary

Exception handling is a very important part of Python programming. By using try-except statements, try-except-else statements, try-except-finally statements, and raise statements, the program can continue to run when an exception occurs, thereby improving the robustness and stability of the program. At the same time, custom exception types can make the code more readable and easier to maintain.

The above is the detailed content of Exception handling techniques in Python. For more information, please follow other related articles on the PHP Chinese website!