c++ - 异常处理相关

Question

I am trying to call terminate function. [I think this function gets called when another exception arises during stack unwinding]. The same scenario I have written and trying to verify.

I am able to see a call being made to terminate() function but i am not sure why i am geting the Debug Error.

While trying to execute the following code in Visual studio 2008, I am getting an error message dialog box "Debug Error". The output is also being displayed:

Output:

In try block

In constructor of A

In constructor of B

In destructor of B

In destructor of A

Call to my_terminate

Why this "Debug Error" window appears while executing this code? It is expected behavior? How to remove this error?

class E
{
public:
      const char* message;
      E(const char* arg) : message(arg) { }
};
void my_terminate() 
{
      cout << "Call to my_terminate" << endl;
};

class A 
{
public:
      A() { cout << "In constructor of A" << endl; }
      ~A() 
      {
          cout << "In destructor of A" << endl;
          throw E("Exception thrown in ~A()");
      }
};

class B 
{
public:

         B() { cout << "In constructor of B" << endl; }
         ~B() { cout << "In destructor of B" << endl; }
};

void main() 
{
      set_terminate(my_terminate);

      try 
      {
        cout << "In try block" << endl;
        A a;
        B b;
        throw("Exception thrown in try block of main()");
      }
      catch (const char* e) 
      {
        cout << "Exception: " << e << endl;
      }
      catch (...)
      {
        cout << "Some exception caught in main()" << endl;
      }

      cout << "Resume execution of main()" << endl;
      getch();
}

Answer 1

您正在从 ~A() 中抛出异常。从析构函数中抛出异常是危险的。如果另一个异常已经在传播，则应用程序将终止。参见 https://stackoverflow.com/a/130123/72178以获得更详细的描述。

Why this "Debug Error" window appears while executing this code?

您正在 try block 中的 main 中抛出异常。这会调用“堆栈展开”并调用 A 和 B 的析构函数。当 ~A() 抛出异常时，应用程序终止。

It is expected behavior?

是的，它是由标准定义的。

How to remove this error?

不要从析构函数中抛出。