Question

Consider the following public method that adds an integer variable to a vector of ints(private member) in a class in C++.

KoolMethod()
{
  int x;
  x = 10;
  KoolList.Add(x);
}
Vector<int>KoolList;

But is this a valid addition to a vector ??? Upon calling the method, it creates a local variable. The scope of this local variable ends the moment the execution control leaves the method. And since this local variable is allocated on a stack(on the method call), any member of KoolList points to an invalid memory location in deallocated stack which may or may not contain the expected value of x. Is this an accurate description of above mechanism ??

Is there a need for creating an int in heap storage using “new” operator everytime a value needs to be added to the vector like described below ????:

KoolMethod()
{
  int *x = new int();
  *x = 10;
  KoolList.Add(x);
}
 Vector<int*>KoolList;   

Answer 1

But is this a valid addition to a vector?

Yes, a (standard library) vector stores copies.

Is there a need for creating an int in heap storage using “new” operator

If you don’t want the objects to be copied or to work with polymorphic objects (see object slicing) you’d use pointers. In that case you should preferably avoid dealing with deallocation manually and use wrappers (smart pointers or pointer containers) though to get exception safety back.