C++ vector of objects vs. vector of pointers to objects

Question

I am writing an application using openFrameworks, but my question is not specific to just oF; rather, it is a general question about C++ vectors in general.

I wanted

Answer 1

If you are allocating memory for the objects using new, you are allocating it on the heap. In this case, you should use pointers. However, in C++, the convention is generally to create all objects on the stack and pass copies of those objects around instead of passing pointers to objects on the heap.

Why is this better? It is because C++ does not have garbage collection, so memory for objects on the heap will not be reclaimed unless you specifically delete the object. However, objects on the stack are always destroyed when they leave scope. If you create objects on the stack instead of the heap, you minimize your risk of memory leaks.

If you do use the stack instead of the heap, you will need to write good copy constructors and destructors. Badly written copy constructors or destructors can lead to either memory leaks or double frees.

If your objects are too large to be efficiently copied, then it is acceptable to use pointers. However, you should use reference-counting smart pointers (either the C++0x auto_ptr or one the Boost library pointers) to avoid memory leaks.