Array of Objects Error

Hello, I made a class and now I want to store instances of those classes in an array. I looked it up and found it was as easy as:
className arrayName[x]When I tried that I got this error:
error: no matching function for call to 'archerTower::archerTower()'|

My class:

Code:

 // class
class archerTower{
    float cX;
    float cY;
    float radius;
    public:
        archerTower(float,float,float);
        float getcX(){return cX;}
        float getcY(){return cY;}
        float getRadius(){return radius;}
};

//constructor
archerTower::archerTower(float x, float y, float r)
{
    cX = x;
    cY = y;
    radius = r;
}

And finally when I try to create the array:
archerTower archerTowerArray[4];Can anyone please help me?