Arrays in the initialization list of a constructor

Question

I'm trying to figure out how to declare an array of an arbitrary size in the constructor's initialization list. If this isn't possible, what should I do instead?

For example:

class vectorOfInt
{
public:

private:
    int _size;
    int _vector[];
};

vectorOfInt::vectorOfInt()
    :_size(32),
    _vector(size)
{
}

Basically, I want the array _vector to be initialized to size (32 in this case). How do I do that? Thanks for any input.

Answer 1

Use an std::vector:

#include <vector>

class vectorOfInt
{
public:

private:
    int _size; // probably you want to remove this, use _vector.size() instead.
    std::vector<int> _vector;
};

vectorOfInt::vectorOfInt()
    :_size(32),
    _vector(size)
{
}

Edit: Since you don't want to use std::vector, you'll have to handle memory yourself. You could use a built-in array if you knew the size of the array at compile time, but I doubt this is the case. You'd have to do something like:

#include <memory>

class vectorOfInt
{
public:

private:
    int _size;
    // If C++11 is not an option, use a raw pointer.
    std::unique_ptr<int[]> _vector;
};

vectorOfInt::vectorOfInt()
    :_size(32),
    _vector(new int[size])
{
}

Answer 2

What you want is to use a vector and then use the 'reserve' keyword. This will allocate space for the 32 elements, and you can initialize them to whatever you want.

#include<vector>
using namespace std;

class vectorOfInt
{
public:

private:
      int _size;
      vector<int> _vector;

vectorOfInt()
{
    _size = 32;
   _vector.reserve(32);

}



};