在C ++中，“throw”和“throw ex”之间有区别吗？ [英] In C++, is there a difference between “throw” and “throw ex”?

问题描述

我想要这个问题（也此处 ），但这次是关于C ++。

C ++之间有什么区别？

  try {/ * some code here * /} 
 catch（MyException& ex）
 {throw ex;} //不只是抛出
  / pre> 
 
 
和
  try {/ * some code here * /} 
 catch（MyException& ex）
 {throw;} //不抛出
  
它只是在堆栈跟踪（C ++中的C＃或Java中的标准）在
 
 
 
（如果它有任何差异，我使用MSVS 2008）。
解决方案
  throw; 重新抛出在 throw ex; 引发新的异常时捕获异常对象。除了创建新的异常对象的性能原因之外，它没有什么不同。如果你有一个例外层次结构，其中有一些其他异常类派生自 MyException 类，同时抛出异常，你已经完成了一个 throw DerivedClassException; 它可以被 catch（MyException&）抓住。现在，如果您修改此捕获的异常对象并使用 throw; 重新抛出异常对象的类型仍将为 DerivedClassException 。如果您执行 throw Ex; ，则会发生对象切片，新抛出的异常将为 MyException 。
 
I'd like to ask this question (also here), but this time about C++.

What is the difference in C++ between 
try { /*some code here*/}
catch(MyException& ex)
{ throw ex;} //not just throw
and
try {  /*some code here*/}
catch(MyException& ex)
{ throw;} //not throw ex
Is it just in the stack trace (which in C++ is in any case not a standard as in C# or Java)?

(If it makes any difference, I use MSVS 2008.)
解决方案
throw; rethrows the same exception object it caught while throw ex; throws a new exception. It does not  make a difference other than the performance reasons of creating a new exception object. If you have a exception hierarchy where there some other exception classes derived from MyException class and while throwing an exception you have done a throw DerivedClassException; it can be caught by the catch(MyException&). Now if you modify this caught exception object and rethrow it using throw; the type of exception object will still be DerivedClassException. If you do throw Ex; the object slicing occurs and the newly thrown exception will be of type MyException.

                        
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