not able to properly overload operator "new" and "delete"?

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Hi,

Thanks very much in advance.
I am working on C++ project in DevC++ environment.

I am trying to overload "new" and "delete" operators but I am unable to call those overloaded operators. Can you please help me identifying where am I making mistake??

C#

void* operator new (size_t , int )// working
{
      cout<<"This is overloaded-new operator"<<endl;
}

void operator delete (void* pointer, int iData)// working
{
     cout<<"This is overloaded-delete operator"<<endl;
}

C#

void main()
{
// as per my understanding following should call overloaded operators
// following gives error: invalid conversion from int to void*
//          initializing argument 2 of void* operator new[](size_t, void*)
void* chObjNew = new(10)char[10];
// following error: type int argument given to delete expected pointer
     delete(chObjNew, 10) ;
}

Posted 8-Feb-12 23:43pm

ggupta2009

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3 solutions

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Lakamraju Raghuram · Accepted Answer · 2012-02-09T00:15:00

Solution 3

I think you have to overload the array form of new as you are allocating for array

C++

void* operator new[](size_t t) 
{
     // ...
}

and similarly delete

C++

void operator delete[](void* ptr
{
   // .....
}

Posted 9-Feb-12 0:15am

Lakamraju Raghuram

Comments

ggupta2009 9-Feb-12 7:17am

Thank you very much.
In this way "new" is working but somehow "delete" is still giving problem.

when I tried hit-and-trial.

following way code is running fine. could you please explain the situation briefly??

void* operator new[] (size_t t, int a)// working
{
cout<<"This is overloaded-new operator"<<endl;
cout<<"Parameter passed to oveloaded-new is: "<<a<<endl;
}

void operator delete (void* pointer, int iData, int iData1)// working
{
cout<<"This is overloaded-delete operator"<<endl;
cout<<"Parameter passed to oveloaded-new is: "<<iData<<endl;
cout<<"Parameter passed to oveloaded-new is: "<<iData1<<endl;
}

void main()
{
void* chObjNew = new(10)char[1];
::operator delete (chObjNew, 13, 14);
}

Output:
This is overloaded-new operator
Parameter passed to oveloaded-new is: 10
This is overloaded-delete operator
Parameter passed to oveloaded-new is: 13
Parameter passed to oveloaded-new is: 14

Lakamraju Raghuram · Accepted Answer · 2012-02-08T23:57:00

Solution 1

Do find excellent explanation with neat exaples at :

http://bytes.com/topic/c/answers/129162-overloading-new-delete-operators[^]

Posted 8-Feb-12 23:57pm

Lakamraju Raghuram

Comments

ggupta2009 9-Feb-12 7:19am

Thanks a lot.
Link is helpful.

Fredrik Bornander · Accepted Answer · 2012-02-09T00:05:00

Solution 2

If you fully qualify your delete it'll work I think:

C++

::operator delete(chObjNew, 10);

Hope this helps,
Fredrik

Posted 9-Feb-12 0:05am

Fredrik Bornander

Comments

ggupta2009 9-Feb-12 7:19am

Thank you very much.
::operator delete(chObjNew, 10); is working

Could you please tell why for "new" we need not to provide global-scope-resolution-operator?

Fredrik Bornander 9-Feb-12 7:41am

I might be going out a limb here but I think they do two different things.
::operator delete deletes the memory allocated to the pointer passed in.
"normal" delete runs the destructor and then runs the ::operator delete.