In C++,if the Base class constructor exception,then the sequence of constructor and destructor could be this?

Question

#include <iostream>
#include <string>
using namespace std;

class Base
{
public:
    Base()
    {
        cout << "Base"<<endl;
    }
    ~Base()
    {
        cout << "~Base"<<endl;
    }

};

class Child: public Base
{
public:
    Child()
    {
        cout << "Child"<<endl;
    }
    ~Child()
    {
        cout << "~Child"<<endl;
    }
};

int main()
{
    try
    {
        Child cc;
    }
    catch(...)
    {
    }

    return 0;
}

the general output will be

Base 
Child
~Child
~Base

But if something terrible or exception caught while Base is constructor ,then is it possible that the sequece will be :

Base 
~Base
Child
~Child

Can anyone write a demo to illustate this? C++ usually doesn't throw exception in the constuctor, but if it does, then could it leads to that output?

Thanks for all helping. I am not sure that in usually code ,this could happens. Is it possible in complicated Base constructor or something wrong or whatever,that will change the usual output ? If so, can anyone give me one example?

I write some test code, but it seems C++ doesn't support stack rescroll, after got exception, the desctructor will not be called. — python
– python, Commented Mar 28, 2013 at 14:48
I write some test code, but after caught exception, the destructor will not be called. Is there a way to illustrate that if something wrong or exception happens while at constuctor Base , the output will be Base() ~Base() Child() ~Child(). — python
– python, Commented Mar 28, 2013 at 14:50

Alok Save · Accepted Answer · 2013-03-28 14:47:41Z

4

If a exception occurs in your Base class constructor no destructors are called.
Simply because there is no complete object that needs to be destroyed!

Can't help but quote Herb on this:

"It cannot die, for it never lived!"

answered Mar 28, 2013 at 14:47

Alok Save

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Comments

fatihk · Accepted Answer · 2013-03-28 14:46:58Z

0

include <stdexcept>
Base()
{
    cout << "Base"<<endl;
    throw std::runtime_error("error");
}

answered Mar 28, 2013 at 14:46

fatihk

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2 Comments

fatihk Over a year ago

He just wanted a test for it so he can find out himself experimentally

python Over a year ago

I tried you way, it seems that after B constructor calls, no other will be called.

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