what's wrong in std::shared_ptr<std::vector<double>>

Question

I am under impressions that std::shared_ptr doesn't free memory when it gets out of scope. Below is my test code. Can you please suggest me what I am doing wrong. I use gtest for testing. When I execute this test I can see that memory is constantly consumed. I use Microsoft VC++ 2013.

    void ProceedVector() {
    std::vector<double> * numbers = new std::vector<double>();
    for (int ind = 0; ind != 10000; ind++) {
        numbers->push_back(ind);
    }
    std::shared_ptr<std::vector<double>> numbersPtr = std::make_shared<std::vector<double>>(*numbers);
}

TEST_F(ManagerTypeConvertorTest, ProceedVector) {
    for (int ind = 0; ind != 50000; ind++) {
        ProceedVector();
    }
}

Answer 1

You have two pointers to two different vectors:

• One which will be deleted (the shared pointer containing a copy of the contents from the first vector)

• And one which will not be deleted (the first vector you create with new).

Answer 2

Each call to ProceedVector does two dynamic allocations of std::vector<double> objects. One here:

std::vector<double> * numbers = new std::vector<double>();

And the other one here:

std::shared_ptr<std::vector<double>> numbersPtr = std::make_shared<std::vector<double>>(*numbers);

make_shared doesn't mean "assign this object to a shared_ptr." It means "allocate a new object from these parameters, and manage the newly allocated object using a shared_ptr."

Depending on what you want the code to achieve, either replace the new line with the make_shared one and don't use a raw pointer at all, or replace the make_shared line with this:

std::shared_ptr<std::vector<double>> numbersPtr{numbers};

That will construct a shared_ptr which will manage the memory pointed to by numbers.