How to use exception filters and exception handling in C#

How to use exception filters and exception handling in C# requires specific code examples

Exceptions are errors or unexpected situations that occur during program running. In C#, exceptions are handled by throwing and catching. Exception handling is a key part of ensuring the normal operation of the program.

In C#, exception filters and exception handling are two common ways to handle exceptions. Exception filters allow us to filter and handle exceptions before catching them. It uses the when keyword to specify the conditions for the exception filter. Here is an example:

try
{
    // 可能抛出异常的代码块
    int a = 10;
    int b = 0;
    int result = a / b;
}
catch (Exception ex) when (ex is DivideByZeroException)
{
    // 异常过滤器，仅处理除零异常
    Console.WriteLine("除零异常：" + ex.Message);
}
catch (Exception ex)
{
    // 其他类型的异常
    Console.WriteLine("其他异常：" + ex.Message);
}

In the above example, we use an exception filter to catch and handle the divide-by-zero exception. If the exception thrown is of type DivideByZeroException, the code in the first catch block will be executed. If it is an exception of other types, the code in the second catch block will be executed.

It is worth noting that the exception filter must be a Boolean expression that returns true or false. If true is returned, it means that the exception meets the filter conditions and will be caught and handled. If false is returned, the exception will continue to be thrown up the upper call stack.

Another common exception handling method is to use finally blocks. The code in the finally block will be executed regardless of whether an exception occurs. Here is an example:

FileStream file = null;
try
{
    file = new FileStream("file.txt", FileMode.Open);
    // 文件操作
}
catch (FileNotFoundException ex)
{
    Console.WriteLine("文件未找到：" + ex.Message);
}
finally
{
    // 无论是否出现异常，都会关闭文件流
    file?.Close();
}

In the above example, we opened a file stream in a try block and then performed file operations. If a FileNotFoundException occurs, the code in the catch block will be executed. If no exception occurs, the code in the finally block will be executed to close the file stream.

Exception handling allows us to handle and recover appropriately when an error occurs in the program. Exception filters and exception handling are two commonly used ways to handle exceptions in C#. Use these techniques to improve the robustness and stability of your program.

I hope the above code examples can help you understand how to use exception filters and exception handling in C#. In the actual coding process, you can choose the appropriate exception handling method to handle exceptions according to specific needs and situations.

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