stack-overflow

void f_ball(float sx, float sy, float r, int n)
{
     al_clear_to_color(black);
     float theta = 0.0;
     float thetainc = 6.283165307/30 ;
     float pX[n], pY[n];
     fstream file;
     file.open("plikxy.txt");
     for(int i=0;i<n;i++)
     {
            theta += thetainc;
            pX[i] = r * cos(theta);
            pX[i] += sx;
            pY[i] = r * sin(theta);
            pY[i] += sy;
            //file<< pX[i] << " " << pY[i] << endl;
    }

    for(int i = 0; i<(n-1); i++)
    {
        for(int j = (i+1); j<n; j++)
        {
            al_draw_line(pX[i], pY[i], pX[j], pY[j], red, 1);
            file<<"Line between "<<pX[i]<<" "<<pY[i]<<" and "<<pX[j]<<" "<<pY[j]<< endl;
        }
    }
    file.close();
    al_flip_display();
}