New derived class from abstract classes - c++

Question

I have encountered a problem with creating new class objects.
The abstract class is called SimpleList, currently doesn't do anything on its own.
template<class T>
class SimpleList {
public:
string ListName;
SimpleList(){
};
string getName(){
return ListName;
};
};
template<class T>
class Queue : public SimpleList<T> {
public:
string ListName;
Queue(string& name){
ListName = name;
}
string getName(){
return ListName;
}
};
And here is where I am attempting to assign 'pQLi' to a new Queue, where Queue is a derived class.
SimpleList<int> *pQLi;
if (indicator == 'i' ){
pQLi = new Queue<int>(name1);
}
But whatever I do to print out the name of pQLi (or access any data from it, but in the simplest case ) outside of the Queue, only ' ' is coming out. For example, if I do this
cout <<(*pQLi).getName() <<"\n";
Instead of printing out the ListName, a blank character comes out

Answer 1

its as simple as it is. Make your base class getName() virtual as follows. Since you are care of the content of pointer, you need a late binding of the object.
template<class T>
class SimpleList
{
public:
string ListName;
SimpleList() = default;
virtual string getName(){
return ListName;
};
};
However, I do not understand, why you need a template class for this. You have not used the type(T) anywhere.
And try to use initializer_list whenever possible and smart pointers are good to use in following cases. I have made a small correction as follows. Hope this has answered your question.
#include <iostream>
template<class T>
class SimpleList
{
private:
std::string ListName;
public:
SimpleList() = default;
virtual ~SimpleList(){}
virtual const std::string& getName()const
{ return ListName; };
};
template<class T>
class Queue : public SimpleList<T>
{
private:
std::string ListName;
public:
Queue(const std::string& name)
:ListName(name) {}
const std::string& getName()const
{ return ListName; }
};
int main()
{
SimpleList<int> *pQLi;
char indicator = 'i';
std::string name1 = "nothing";
if (indicator == 'i' ){
pQLi = new Queue<int>(name1);}
std::cout <<(*pQLi).getName() <<"\n";
delete pQLi;
pQLi = nullptr;
return 0;
}