Fifth. Exception handling of the management program flow (in. net4.5)

1. Overview

This chapter includes parts related to exception handling in. net4.5.

2. Main content

　　2.1 Handling Exceptions

①try, Cahtch, finally mechanism, need not say much.

② using the Environment.failfast method, you can immediately terminate the program and write to the system event log. Will bypass the finally execution.

 Public Static voidMain () {strings =Console.ReadLine (); Try    {        inti =int.        Parse (s); if(i = = the) environment.failfast (  "Special number entered. "); }      finally{Console.WriteLine ("Program Complete ."); }      }

③ if the code in finally has an exception, it will be thrown into the outer handler and the initial exception information will be lost.

　　2.2 Throwing Exceptions

① do not attempt to reuse exception objects, especially in multithreaded environments. Because the stack information for the exception may be changed by other threads.

②c#5 adds a new Exceptiondispatchinfo.throwthat will save the original exception information and throw it up. It is mainly used for passing exception information between threads.

NULL ; Try {    string s = console.readline ();     int  . Parse (s);} Catch (FormatException ex) {    = exceptiondispatchinfo.capture (ex);} if NULL )    Possibleexception.throw ();

③ exception handling can affect program flow and performance and reduce readability.

④ some exceptions that can only be thrown by the runtime: Airthmaticexception, ArrayTypeMismatchException, DivideByZeroException,

IndexOutOfRangeException, InvalidCastException, NullReferenceException, OutOfMemoryException,

OverflowException, StackOverflowException, TypeInitializationException.

　　2.3 Creating a Custom exception

Custom exceptions should follow the rules, ending with exception. The serialization attribute should be added. Do not inherit from System.ApplicationException.

[Serializable] Public classorderprocessingexception:exception, iserializable{ PublicOrderprocessingexception (intorderId) {OrderId=orderId;  This. HelpLink ="Http://www.mydomain.com/infoExps"; }     PublicOrderprocessingexception (intOrderId,stringmsg):Base(msg) {OrderId=orderId;  This. HelpLink ="Http://www.mydomain.com/infoExps"; }     PublicOrderprocessingexception (intOrderId,stringmsg, Exception innerexp):Base(msg, innerexp) {OrderId=orderId;  This. HelpLink ="Http://www.mydomain.com/infoExps"; }    protectedorderprocessingexception (SerializationInfo info, StreamingContext context) {OrderId= (int) info. GetValue ("OrderId",typeof(int)); }     Public intOrderId {Get;Private Set;}  Public voidGetObjectData (SerializationInfo info, StreamingContext context) {info. AddValue ("OrderId", OrderId,typeof(int)); }}    

3. Summary

① in. NET, exceptions should be handled with the exception handling mechanism provided.

② should use a try block with one or more catch blocks to handle different types of exceptions.

③ a custom exception should be used only when it is determined that the user of the code will be able to handle it logically. Otherwise, the built-in exception type should be used.

Fifth. Exception handling of the management program flow (in. net4.5)