Question

I am dynamically allocating memory for an array in a function. My question is: once the function finishes running is the memory freed?

code:

void f(){
    cv::Mat* arr = new cv::Mat[1];
    ...
}

Answer 1

No, it is not. You must free it by calling

delete[] arr;

But you should ask yourself whether it is necessary to allocate dynamically. This would require no explicit memory management:

void f(){
    cv::Mat arr[1];
    ...
}

If you need a dynamically sized array, you could use an std::vector. The vector will internally allocate dynamically, but will take care of de-allocating it’s resources:

void f(){
    std::vector<cv::Mat> arr(n); // contains n cv::Mat objects
    ...
}