delete memory

Monark

Hi All, I am new to c++ and facing one prob. I have one base class Vehicle and two sub class Car and Motor. I have an array of pointer to sub class but i m not able to delete the memory for that. CVehicle CCar : CVehicle CMotor : CVehicle CVehicle** myVehicle; myVehicle = new CVehicle*[3]; myVehicle[0] = new CCar; myVehicle[1] = new CMotor; myVehicle[2] = new CCar; now when I tried to reallocate the memroy, it is giving an error. delete myVehicle ; Any idea how to delete the memory?? Any help Monark - I am learning

sw thi

When you are deleting an array of elements that you created using new, you should be doing it using '[]' delete []variable;

toxcct

when you use new, you must use delete. when you use new[], you must use delete[]. BTW, i see a problem in your design. a Car is actually a Vehicle, so, it's ok to derive it from CVehicle. but a Motor is not a Vehicle. a Vehicle HAS A Motor... it seems that you confused with the IS A relationship. also, are you sure to wanting to create an array of pointers rather than an array of objects ?

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Nishad S

You need to deallocate as delete myVehicle[0]; delete myVehicle[1]; delete myVehicle[2]; delete [] myVehicle;

- NS -

KarstenK

use the delete operator carefully. With delete you delete pointers: first delete myVehicle[0]; delete myVehicle[1]; delete myVehicle[2]; delete *myVehicle;//pointer to pointer Hammer in your head: to every new belongs a delete :-O

Greetings from Germany

David Crow

KarstenK wrote:

delete *myVehicle;//pointer to pointer

Your syntax is a bit askew. Use:

delete [] myPointer;

"A good athlete is the result of a good and worthy opponent." - David Crow

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

KarstenK

I chose this way use the same syntax as the declararion: to make it easier readable

Greetings from Germany

David Crow

KarstenK wrote:

I chose this way use the same syntax as the declararion: to make it easier readable

But it is wrong. As the address being deleted is not the same as the one allocated, you will receive an access violation.

"A good athlete is the result of a good and worthy opponent." - David Crow

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne

KarstenK

it was (not my code as followed) allocated: CVehicle** myVehicle; myVehicle = new CVehicle*[3]; so I would delete *myVehicle; or would I get (a deservred) exception :~

Greetings from Germany

David Crow

You're missing it entirely. myVehicle and *myVehicle point to two different addresses, with the latter already having been freed (via delete myVehicle[0]). Rather than guess at what you are trying to do, why not just try it?

"A good athlete is the result of a good and worthy opponent." - David Crow

"To have a respect for ourselves guides our morals; to have deference for others governs our manners." - Laurence Sterne