Using an int as a template parameter that is not known until run-time

Question

I am trying to use an integer as a template parameter for a class. Here is a sample of the code:

template< int array_qty > 
class sample_class {

    p         


        

Answer 1

I'm a little late, but here's my suggestion. I'm guessing the main problem with vectors for you is that they allocate a larger capacity than what you need in order to support dynamic growth. So, can't you write your own simple array class?

template 
class Array {
    private: 
        T* data; 
        unsigned size; 
    public: 
        Array(unsigned size) {
            data = new T[size]; 
            this->size = size; 
        }
        T& operator[](int i) {
            return data[i]; 
        }
        T operator[](int i) const {
            return data[i]; 
        }

        // Depending on your needs, maybe add copy constructor and assignment operator here.
        ...

        unsigned size() {
            return size; 
        }

        ~Array() {
            delete [] data; 
        }
}

From what I know, I believe this should be just as fast as the STL array class. In addition, you can create Arrays with sizes unknown until run-time, the Array's memory is handled automatically when it is destroyed, and you don't have to instantiate a new class every time you create a new array with a different size (like you have to do for STL arrays).