Set the bounds of an array after object initialisation in cpp

I’m working on an image renderer in cpp that I wrote from scratch (I don’t want to use anything but standard libraries), but I’m having some trouble when trying to store the image. The class I use to store images looks like this:

class RawImage
{
    private:
        RGB pixels[][][3] = {};
    public:
        int width = 0;
        int height = 0;
        RawImage(int width, int height)
        {
            this->width = width;
            this->height = height;
        };
        RGB GetPixel(int x, int y)
        {
            if (x < 0 || x > width - 1)
                return RGB(0.f, 0.f, 0.f);
            if (y < 0 || y > height - 1)
                return RGB(0.f, 0.f, 0.f);
            return pixels[x][y];
        };
        int SetPixel(int x, int y, RGB color)
        {
            if (x < 0 || x > width - 1)
                return -1;
            if (y < 0 || y > height - 1)
                return -1;
            this->pixels[x][y] = color;
            return 0;
        }
};

When I try to compile this code, the g++ compiler gives the following error: declaration of ‘pixels’ as multidimensional array must have bounds for all dimensions except the first.

How do i use a multidimentional array of wich the 2 first dimensions vary in size, but the third dimension is of a fixed size?

>Solution :

Set the bounds of an array after object initialisation in cpp

The size of an array never changes through its lifetime. It’s set upon creation. Technically this isn’t a problem for you because you can initialise the array in the constructor.

But, size of an array variable must be compile time constant, so you cannot accept the size as a constructor parameter.

You can use a dynamic array. Most convenient way is to use std::vector.