如何实例化对象并让它们在 scope 之外仍然可用？ （例如在循环中实例化一个 object）

Question

I'm trying to write a program that takes in user input and uses it to create objects that are then pushed to a list. Here is a simplified version of what I wrote:

int main(){
  cout << "How many lists? \n";
  int numLists;
  cin >> numLists;
  list<MyObject> objectList;

  for(int i = 0; i < numLists; i++){
    cout << "Enter some input for list #" << i << "! \n";

    int n = 3;

    while(n-- != 0){
      int input;
      cin >> input;
      MyObject object(input);
      objectList.push_back(object);
    }
    //Save the newly created list somewhere
  }
  //Do something with all the created lists
}

Once the loop finishes, the objects created inside of the loop end up out of scope and the list has size zero.

I started using

list<MyObject> *list = new list<MyObject>
...
MyObject *object = new MyObject(input);
...
(*list).push_back(*object);

and it seems to be working fine, but I was wondering if there was a better way to achieve this. Furthermore, since I am using multiple instances of list and MyObject outside of the loops from which they were created, how do I clear the memory?

Thank you

Answer 1

Read up on scope for C++ here: https://en.cppreference.com/w/cpp/language/scope

Why do you want to reference objects made in the for loop? They have already been copied into the list<> object, so you can read/modify them there.