C++ Vector of Derived Class Objects (without pointer) possible?

Asked Jan 06 '15 at 09:16

Active Jan 06 '15 at 09:20

Viewed 52 times

I have a base class A and some classes B, C, ... which inherits from A. I would like to know if I am obliged to use polymorphism to store some derived class objects in a vector for example.

The standard way is:

std::vector<A*> myVector;
A* obj1 = new B;
A* obj2 = new C;
myVector.push_back(obj1);
myVector.push_back(obj2);

However, if I don't need to use polymorphism can I do?

std::vector<A> myVector;
B obj1;
C obj2;
myVector.push_back(obj1);
myVector.push_back(obj2);

edited Jan 06 '15 at 09:20

Kerrek SB

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asked Jan 06 '15 at 09:16

DarkVapor

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Your "standard way" is awful. It should be `std::vector>`. And yes, it requires a virtual destructor. – Kerrek SB Jan 06 '15 at 09:18
Possible duplicate: http://stackoverflow.com/q/274626/596781 – Kerrek SB Jan 06 '15 at 09:18
1

You can also implement a type which internally holds a pointer to a polymorphic implementation, and give it value semantics. – juanchopanza Jan 06 '15 at 09:22
Thank you Kerrek. Why is it awful? – DarkVapor Jan 06 '15 at 09:22
http://stackoverflow.com/questions/11889178/c-can-vectorbase-contain-objects-of-type-derived – Retired Ninja Jan 06 '15 at 09:24
Thank you Retired Ninja, didn't find that one when I posted ! – DarkVapor Jan 06 '15 at 09:25
Using naked pointers in STL containers leads to memory leaks, primarily, if you aren't careful. You have to explicitly delete them. And if you are using STL calls like `erase` or `remove` then it becomes quite twisted to guarantee safe behavior. – DumbCoder Jan 06 '15 at 10:13
Thank you DumbCoder. I am not familiar with the STL, I mainly use the QTL :) – DarkVapor Jan 06 '15 at 10:36

C++ Vector of Derived Class Objects (without pointer) possible?

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