Question

how can declare a 2nd or multidimensional array without first size in c++?

class numeric 
{
    public:
    int int_array_numbers[][];
    ...
};

Error message:
declaration of ‘int_array_numbers’ as multidimensional array must have bounds for all dimensions except the first

Answer 1

you can declare your class as template from two arguments
something like this

template <int N, int M>
class numeric 
{
public:
     int int_array_numbers[N][M];
...
};