Question

Class A{
public:
      int a;
      vector<A> test;
};

Class B{
public:
      B();
      B(const B &rhs);
      ~B();
      B & insertTest(A element,A element1) {
        element.test.pushback(element1); //doesn't work
      }
      B & insertTest1(A element) {
        test1.pushback(element);//works
      }; 
private:
      vector<A> test1;
};

I’m trying to insert elements to these two vectors. It works when i insert element to vector test1 in class B. However, I can’t get value after inserting to the vector in Class A.

Answer 1

The following doesn’t work because element is passed by value

      B & insertTest(A element,A element1) {
        element.test.push_back(element1); //doesn't work
      }

The following works since you are modifying test1, which is a member of this

      B & insertTest1(A element) {
        test1.push_back(element);//works
      }; 

If you want the first to work, pass element by reference, like this:

      B & insertTest(A& element,A element1) {
        element.test.push_back(element1);
      }