C++ Set size of an array data member at initialization of class

Question

I need to make a class that has an array as a data member. However I would like to make it so that the user can choose the size of the array when an object of that class is created. This doesn't work:

class CharacterSequence {

private:

  static int size;
  char sequence[size];

public:

  CharacterSequence(int s) {
    size = s;
  }

};

How would I do this?

Answer 1

Use a std::vector:

class CharacterSequence
{
private:
    std::vector<char> _sequence;

public:
    CharacterSequence(int size) : _sequence(size)
    {
    }
}; // eo class CharacterSequence

Answer 2

Others have suggested using a std::vector... but I don't think that's what you really want. I think you want a template:

template <int Size>
class CharacterSequence {

private:

  char sequence[Size];

public:

  CharacterSequence() {
  }
};

You can then instantiate it to whatever size you want, such as:

CharacterSequence<50> my_sequence;