类的定义问题，高手来看下啊！

#include   <iostream.h>
#include  <math.h>
class  point
{
    public:
      float x,y,z;
    public:
      point(float a=3,float b=4,float c=5);
      point(point &p);
    void   negate(float m,float n,float k);
    void   norm(double l);
    void   print();
    
};
point::point(float a,float b,float c)
      {
          x=a;
          y=b;
          z=c;
      }
point:: point(point &p)
  {
          x=p.x;
          y=p.y;
          z=p.z;
  }
void point::negate(float m,float n,float k)
{
    m=-x;
    n=-y;
    k=-z;
    cout<<"这个点关于远点的对称点是：";
    cout<<"("<<m<<","<<n<<","<<k<<")"<<endl;
}
void   point::norm(double l)
{

    l=sqrt(x*x+y*y+z*z);
    cout<<"这个点和原点的距离是："<<l<<endl;
}
void  point::print()
{
cout<<"这个点是："<<"("<<x<<","<<y<<","<<z<<")"<<endl;
}
void main()
{
point t1(2,3,4);

point t2(t1);
t1.norm;
t2.print;

}
这个程序可以通过编译，没错误，但是有警告，尤其是三个成员函数，不能调用，说是函数引用什么的，麻烦高手解读下，