Exception handling of classes in C ＃

Welcome to be my reader , I hope this article can give you some help .

Preface

During the daily coding process , The most important skill is not that you learn to use many of the latest programming techniques or make a tall system . It's when you're writing code , Handling of exceptions , Whether the system can be stable , robust .

For exception handling in C# China is through try/cath Mechanism to capture , Let's take a look at .

An exception is a runtime error in a program , It violates system constraints or application constraints , Or something unexpected in normal operation .

For example, abnormal assignment of some variables or errors during operation .

abnormal

About anomalies , stay C# Pass through try Statement and exception handling mechanism class ensure exception capture , Prevent the whole program from being reminded of exceptions due to the non capture of exceptions , Even collapse .

Unusual requirements

• try Blocks contain code that is protected from exceptions
• catch The clause section contains one or more catch Clause .( The exception handling code segment is also called exception handling subroutine )
• finally Blocks contain code to be executed in all cases , Whether there is any abnormality or not

class Program
{
    static void Main(string[] args)
    {
        try
        {
            // Verify whether there is abnormal code 
            Ahui hui = new Ahui();
            InfoBase info = (InfoBase)hui;

            Console.WriteLine(hui.GetInfo());
            Console.WriteLine(info.GetInfo());
        }
        catch (Exception ex)
        {
            // Capture exception , Handle exceptions 

            throw new Exception(" An exception is thrown up one level ！");
        }            
        Console.ReadKey();
    }
}

When processing business code , Logical errors must be considered clearly at the beginning for verification , For example, judge empty , Abnormal value , Wrong value type, etc .

Secondly, through try/catch Mechanism to catch abnormal exceptions , Prevent the program from making uncontrollable errors , Leading to a rout .

Tips ： Use exceptions as little as possible to catch in business programs , If the conditions are met, the exception should be handled in advance as soon as possible .<Catch() The exception handling time in will be relatively long , And it will lead to the waste of system resources （ Exceptions are thrown up in real time ）.>

stay C# There are many different types of exceptions that can occur in ,BCL Many classes are defined , Each class represents a specified exception type . When an exception occurs ,CLR First create an exception object of this type , Second, find the right catch Clause to handle it .( All exception classes are derived from System.Exception class )

About catch() There are three forms , Can handle different levels of exceptions .

The first one is General exception handling

   try
   {

   }
   catch
   {
       // General exception handling 
       
   }

Can accept any exception , But we can't confirm the type of exception . The possible exceptions can be handled and cleaned up .

The second kind Specific exception handling

    try
    
    }
    catch(Exception)
    {
        // Specific exception handling 
        
    }

Take the name of an exception class as a parameter , An exception that matches the specified class or an exception class derived from it .

The third kind of Specific exception handling with object

    try
    
    }
    catch(Exception ex)
    {
        
      throw new Exception(ex.Message);
    }

A variety of exception information about exceptions can be provided , An exception that matches the specified exception or an exception class derived from it . Through the exception instance , You can get the details of the exception .

    try
    
    }
    catch (Exception ex)
    {
        // Specific exception handling 
        throw new Exception(ex.Message);
    }
    finally { 
        // The handling mechanism after an exception occurs 

    }

Here's a special explanation , About finally The code in , Whether the exception is caught or not , It will be executed .

stay finally Code suitable for releasing resources or subsequent processing .

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remarks

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