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c++opencv3.0expectation-maximization

How to read const &vector<Mat> data type from EM::getCov(&vector<Mat>) for c++

I am trying to get the result of this function:

C++: 

void EM::getCovs(std::vector<Mat>& covs) const

My question is how to get the covs? I kept getting compiling error. Here is my code.

const vector<Mat> &covs;
model->getCovs(covs);

I get error said

Declaration of reference variable 'covs' requires an initializer.

(1) This is the correct way to get data from getCovs, or

(2) I need to initialize 'covs' like the error showed.

Solution

  • The & in the parameter list void getCovs(std::vector& covs) means that you pass a reference to an existing vector.

    You should declare local storage for a vector:

    vector<Mat> covs;

    then you can pass a reference to it into getCovs:

    model->getCovs(covs);

    What you wrote (vector<Mat>& covs;) is a local variable that references another vector; however you haven't provided another vector for it to reference. The const also prevents it from being modified, but you want it to be modified by the getCovs function.