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Asked: 2026-05-15T13:32:05+00:00

I particularly like the simplicity of using STL containers in the straightforward way. I

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I particularly like the simplicity of using STL containers in the straightforward way.

I have never really figured out how to get the Boost library working on my dev platforms, in fact I don’t think I’ve even tried. I guess you could say I am just trying to delay the inevitable since Boost is clearly a helpful library that I should be using.

But my question is essentially the same as this topic: How to initialise a STL vector/list with a class without invoking the copy constructor

I have std::list<ExpensiveClass> mylist; and I just want a function that pushes a new instance into the list and calls the default constructor, rather than copying it from a temporary stack instance of it. In the other topic there was mention of move constructors. I looked them up and quite frankly it does nothing but strike fear into my heart. Two ampersands!!

Would it work if I just made an array of ExpensiveClass objects? ExpensiveClass *mylist = new ExpensiveClass[20]; Does this call the constructor 20 times?

Seems to me I should just use boost:ptr_list.

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1 Answer

  1. Editorial Team

    Inserting an object into a container invokes the copy constructor on that object. There’s really no way around that (yet), hence why pointer containers are used for large objects: it’s dirt cheap to copy a pointer.

    If you choose to use a container of smart pointers, you can either use one of the Boost pointer containers or you can use an STL container of shared_ptrs.

    To answer your question about:

    ExpensiveClass *mylist = new ExpensiveClass[20];

    The default constructor for ExpensiveClass is called 20 times: once for each element of the array.

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