求大神指教，这个程序错在哪里了？

cube.h
class cube
{
private:
static double Number;
double m_lenth;
double m_height;
double m_wide;
double m_bulk;
public:
static double getnumber();
void printcube();
cube(double m_lenth,double m_height,double wide);
double getbulk();
~cube();
};
cube.cpp
#include"cube.h"
#include<iostream>
using namespace std;
double cube::Number=0;
cube::cube(double lenth,double height,double wide)
{
m_lenth=lenth;
m_height=height;
m_wide=wide;
m_bulk=m_lenth*m_height*m_wide;
Number++;
}
double cube::getnumber()
{
return getnumber;
}
double cube::getbulk()
{
return getbulk;
}
void cube::printcube()
{
cout<<"立方体的长、宽、高分别为:"<<m_lenth<<m_height<<m_wide<<endl;
cout<<"立方体的体积为:"<<m_bulk<<endl;
}
cube::~cube()
{
Number--;
}
test.cpp
#include<iostream>
#include"cube.h"
using namespace std;
int main()
{
cube a1(1,1,1);
cube a2(2,2,2);
cube a3(3,3,3);
a1.printcube();
a2.printcube();
a3.printcube();
cout<<"立方体个数为:"<<cube::getnumber()<<endl;
return 0;
}