Can I cast a pointer from a unknow type ?

[Santosh Reddy]

As high_flyer mentioned, you not very clear in how inheritance in C++ works, (or at-least how to use it, in your case).

Baseclass *entity = new Baseclass;

Baseclass *entity = new Baseclass;

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This is not correct, you should be using new DerivedClass, or a factory method to create object and get it's base class pointer. If you do it this way, you are basically creating a BaseClass Object and store it in BaseClass pointer, where as you want to create a DerivedClass object, and store it in BaseClass pointer.

*entity = *dynamic_cast<(typeid(m_listEntities.at(m_listEnti ties_selected[i]) ) )> (m_listEntities.at(m_listEntities_selected.at(i))) ;//errors

This is not possible, you need to know the type at compile time to cast it to, where as typeid operator returns a type_info class object (which happens at runtime), and again which is of type type_info, not your BaseClass (as you expect)

you can use the typeid operator to get type information like, this

typeid(int).name()
typeid(derived).name() //parameter can be object, class, or object pointer..
if(typeid(object1) == typeid(object2)) //this is run time object creation, and uses the type_info class == operator to compare the objects
...

Conclusion:
To create a DerivedClass object, you cannot avoid if..else (or switch case), to know the type(or other criteria) to create object. The best practice is either have factory class, or a factory method, which is the solution provided by the factory design pattern for your problem.

I suggest you reading about factory design pattern, which is cleaner, maintainable (adding new derived classes in future) solution to your problem.