第三届中国古村镇大会:看看这个c++程序是怎么回事

class Complex
{
private:
float real,imag;
public:
Complex() {real=0.0;imag=0.0;}
Complex(float r,float i) { real=r;imag=i;}
void print();
friend Complex operator+(Complex a,Complex b);
friend Complex operator-(Complex a,Complex b);
friend Complex operator*(Complex a,Complex b);
friend Complex operator/(Complex a,Complex b);
};
#include"Complex.h"
#include"iostream.h"

void Complex::print()
{
cout<<real;
if(imag>0) cout<<"+";
if(imag!=0) cout<<imag<<"i";
else cout<<endl;
}

Complex operator+(Complex a,Complex b)
{
Complex temp;
temp.real=a.real+b.real;
temp.imag=a.imag+b.imag;
return temp;
}
Complex operator-(Complex a,Complex b)
{
Complex temp;
temp.real=a.real-b.real;
temp.imag=a.imag-b.imag;
return temp;
}
Complex operator*(Complex a,Complex b)
{
Complex temp;
temp.real=a.real*b.real-a.imag+b.imag;
temp.imag=a.real*b.imag+a.imag*b.real;
return temp;
}
Complex operator/(Complex a,Complex b)
{
Complex temp;
float ftemp;
ftemp=1/(b.real*b.real+b.imag*b.imag);
temp.real=(a.real*b.real)*ftemp;
temp.imag=(b.real*a.imag-b.imag*a.real)*ftemp;
return temp;
}
#include"Complex.h"
void main()
{
Complex c1(1.5,2.5),c2(5,15),c3;
c1.print();
c2.print();
c3.print();
c3=c1+c2;
c3.print();
c3=c1-c2;
c3.print();
c3=c1*c2;
c3.print();
c3=c1/c2;
c3.print();
}
编译程序通过.执行时出现错误
Linking...
main.obj : error LNK2001: unresolved external symbol "class Complex __cdecl operator/(class Complex,class Complex)" (??K@YA?AVComplex@@V0@0@Z)
main.obj : error LNK2001: unresolved external symbol "class Complex __cdecl operator*(class Complex,class Complex)" (??D@YA?AVComplex@@V0@0@Z)
main.obj : error LNK2001: unresolved external symbol "class Complex __cdecl operator-(class Complex,class Complex)" (??G@YA?AVComplex@@V0@0@Z)
main.obj : error LNK2001: unresolved external symbol "class Complex __cdecl operator+(class Complex,class Complex)" (??H@YA?AVComplex@@V0@0@Z)
main.obj : error LNK2001: unresolved external symbol "public: void __thiscall Complex::print(void)" (?print@Complex@@QAEXXZ)
Debug/main.exe : fatal error LNK1120: 5 unresolved externals
执行 link.exe 时出错.

main.exe - 1 error(s), 0 warning(s)
请高手指点