C # Advanced Programming 82-day----user-defined exception class

User-defined Exception class

There have been a lot of questions about anomalies , so let's talk about the why did of custom exceptions .

Why does a custom exception class appear ? use your toes to think and understand . , is to define our own anomalies. , Custom exception classes inherit from ApplicationException

The first exception (Exception) is divided into two categories , one of which is the predefined exception class , which is the class that needs to be inherited when the user customizes the exception class .

Case :

Using System;

Using System.Collections.Generic;

Using System.Linq;

Using System.Text;

Using System.Threading.Tasks;

Namespace Custom Exception classes

{

Class Program

{

static void Main (string[] args)

{

or the case of the previous sentence?

Console.WriteLine (" Enter a number from 0 to 5 :");

Try

{

you must have known that.

If you don't know , you can see the meaning of Parse , and don't expect me to say anything !

int num = Int. Parse (Console.ReadLine ());

if (num < 0 | | num > 5)

{

throw new MyException (" Are you funny ?") tease me. ?");

}

}

catch (MyException ex)

{

Console.WriteLine (ex. Message);

}

catch (Exception ex)

{

Console.WriteLine (ex. Message);

}

Finally

{

Console.WriteLine (" I'm still the finally of the Ox X !");

}

Console.readkey ();

}

}

public class Myexception:applicationexception

{

Public myexception () {}

Public myexception (String message): base (message) {}// did you know it was a dry word ? don't tell me you forgot. !!

public override string Message

{

Get

{

Return base. Message;

}

}

}

}

In this custom exception class myexception:applicationexception,catch( MyException me) user captures a custom exception,catch(Exception e) is used to catch a generic exception if the exception is first catch capture, the second catch will not execute, directly execute The statement in finally.

Here are a few things to note about custom exception classes :

1. If your exception class is required to write to a file , such as a log , you need to declare the exception class as serializable [Serializable]

2. To implement a parameterless constructor , because a parameterless exception may be thrown

3. Implement a constructor that contains a message

4. Implement a constructor that contains the message and the inner exception type

5. Add your own from the error identification data member

So , in general, the custom format is like this

Class Myexception:applicationexception

{

This is a non-parametric constructor , try it .

Public MyException ()

{ }

Public myexception (String message)

: Base (Message)

{ }

Public myexception (String message, Exception inner)

: Base (message, inner)

{ }

}

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C # Advanced Programming 82-day----user-defined exception class