帮忙看看这个程序怎么修改？

[Impr]

#include <iostream.h>
class Animal

void Setvalue(Animal &int);
void Setvalue(Animal&,int,int);

class Animal
{
public:
friend void setvalue(Animal&,int);
protected:
int itsweight;
int itsage;
};
void Setvalue(Animal& ta,int tw)
{
ta.itsweight=tw;
}
void Setvalue(Animal& ta,int tw,int tn)
{
ta.itsweight=tw;
ta.itsage=tn;
}
int main()
{
Animal peppy;
Setvalue(peppy,5);
Setvalue(peppy,7,9);
return 0;
}

[無_1024]

#include <iostream.h>
class Animal;

void Setvalue(Animal&,int,int);

class Animal
{
public:
	friend void setvalue(Animal&,int);
	void setWeight( int w)
	{
		itsweight = w;
	}
	void setAge( int a)
	{
		itsage = a;
	}
protected:
	int itsweight;
	int itsage;
};
void Setvalue(Animal& ta,int tw)
{
	ta.setWeight(tw);
}
void Setvalue(Animal& ta,int tw,int tn)//非友元函数不能直接调用protected成员
{
	ta.setWeight(tw);
	ta.setAge(tn);
}
int main()
{
	Animal peppy;
	Setvalue(peppy,5);
	Setvalue(peppy,7,9);
	return 0;
}

[nickxzh]

#include <iostream.h>
class Animal;

void Setvalue(Animal&,int,int);

class Animal
{
public:
friend void setvalue(Animal &obj,int i1, int i2=0);//这样就正确了
void setWeight( int w)
{
itsweight = w;
}
void setAge( int a)
{
itsage = a;
}
protected:
int itsweight;
int itsage;
};
void Setvalue(Animal& ta,int tw)
{
ta.setWeight(tw);
}
void Setvalue(Animal& ta,int tw,int tn)//非友元函数不能直接调用protected成员
{
ta.setWeight(tw);
ta.setAge(tn);
}
int main()
{
Animal peppy;
Setvalue(peppy,5);
Setvalue(peppy,7,9);
return 0;
}