How to print total memory allocated for an object

[rsodimbakam]

Hi,
class Sample
{
int x, *ptr;
public:
Sample()
{
ptr = new int[100];
}
~Sample()
{
}
};
int main()
{
cout << "SizeofClass" << sizeof(Sample); //gives me output 8
Sample sm;
cout<< "SizeofObject" << sizeof(sm); //also gives me output 8


}

But i assume the size of sample object should be 4(x) + 400(ptr) = 404 bytes

Is there anyway that i can know or print the total memory alloacted which

x + ptr = 4 +400 = 404 bytes

Is my assumption correct ? Pls clarify me on this

Thanks
Kiran

[Hobson]

It is not possible by any standard means. You'd have to either implement your solution based on size tracking of all dynamically allocated objects, or use some platform dependent ways (_msize for heap arrays, etc.)

Cheers

[rsodimbakam]

So, is it mean the size of an object is always caluculated at compile time irrespective of whether it contains a normal member variable or pointer variables ?

Any exception is there for this case ?

[Paul McKenzie]

So, is it mean the size of an object is always caluculated at compile time irrespective of whether it contains a normal member variable or pointer variables ?

Yes. The sizeof() is a compile-time constant.

Any exception is there for this case ?

No.

Regards,

Paul McKenzie

[Speedo]

But i assume the size of sample object should be 4(x) + 400(ptr) = 404 bytes

In that particular example the actual memory used would be

sizeof(int) + sizeof(int*) + sizeof(int)*100

which is,

x + ptr + (memory allocated to ptr)

[Lindley]

+ any padding the compiler decides to add to the struct