请教高手：C++中重载函数的问题

#include <iostream.h>

class point{
    float x,y,z;
 public:
    point(float x=0,float y=0,float z=0){
     this->x=x;  this->y=y;  this->z=z;
    }
    ~point(){};

    float getx(){return x;}
    float gety(){return y;}
    float getz(){return z;}
    void  setx(float t){x=t;}
    void  sety(float t){y=t;}
    void  setz(float t){z=t;}
};
int main(int argc, char *argv[])
{
    point A(5,10),B(5,10,12);

    cout<<"二维点操作:\nA=("<<A.getx()<<","<<A.gety()<<")\n";
    cout<<"二维点操作:\nA=("<<A.getx()<<","<<A.gety()<<","<<A.getz()<<")\n";
    cout<<"三维点操作:\nA=("<<B.getx()<<","<<B.gety()<<","<<B.getz()<<")\n";
    
    return 0;
}

执行结果：
E:\C++>project1.exe
二维点操作:
A=(5,10)
二维点操作:
A=(5,10,0)
三维点操作:
A=(5,10,12)