c++ fatal error LNK112 error LNK2019: 无法解析的外部符号

#include
using namespace std;
class Boy
{
public:
Boy(char name,int year);
Boy(const Boy&pp);
~Boy();
char getName(){return name;}
int getYear(){return year;}
private:
char name;
int year;
};
Boy::Boy(char name,int year):name(name),year(year){}
Boy::Boy(const Boy&pp)
{
name=pp.name;
year=pp.year;
}
class Girl
{
public:
Girl(char name,int year);
Girl(const Girl &p);
~Girl();
char getName(){return name;}
int getYear(){return year;}
friend class Boy;
void visitBoy(Boy&boy);
private:
char name;
int year;
};
Girl::Girl(char name,int year):name(name),year(year){}
Girl::Girl(const Girl&p )
{
name=p.name;
year=p.year;
}
void Girl::visitBoy( Boy&boy)
{
char name=boy.getName();
cout<}
int main()
{
Girl girl('g',16);
Boy boy('j',45);
girl.visitBoy(boy);
return 0;
}
显示
#include
using namespace std;
class Boy
{
public:
Boy(char name,int year);
Boy(const Boy&pp);
~Boy();
char getName(){return name;}
int getYear(){return year;}
private:
char name;
int year;
};
Boy::Boy(char name,int year):name(name),year(year){}
Boy::Boy(const Boy&pp)
{
name=pp.name;
year=pp.year;
}
class Girl
{
public:
Girl(char name,int year);
Girl(const Girl &p);
~Girl();
char getName(){return name;}
int getYear(){return year;}
friend class Boy;
void visitBoy(Boy&boy);
private:
char name;
int year;
};
Girl::Girl(char name,int year):name(name),year(year){}
Girl::Girl(const Girl&p )
{
name=p.name;
year=p.year;
}
void Girl::visitBoy( Boy&boy)
{
char name=boy.getName();
cout<}
int main()
{
Girl girl('g',16);
Boy boy('j',45);
girl.visitBoy(boy);
return 0;
}
#include
using namespace std;
class Boy
{
public:
Boy(char name,int year);
Boy(const Boy&pp);
~Boy();
char getName(){return name;}
int getYear(){return year;}
private:
char name;
int year;
};
Boy::Boy(char name,int year):name(name),year(year){}
Boy::Boy(const Boy&pp)
{
name=pp.name;
year=pp.year;
}
class Girl
{
public:
Girl(char name,int year);
Girl(const Girl &p);
~Girl();
char getName(){return name;}
int getYear(){return year;}
friend class Boy;
void visitBoy(Boy&boy);
private:
char name;
int year;
};
Girl::Girl(char name,int year):name(name),year(year){}
Girl::Girl(const Girl&p )
{
name=p.name;
year=p.year;
}
void Girl::visitBoy( Boy&boy)
{
char name=boy.getName();
cout<}
int main()
{
Girl girl('g',16);
Boy boy('j',45);
girl.visitBoy(boy);
return 0;
}

~Boy();//这个是你原来的 Boy类的析构 改成下边这样
~Boy()
{

}
~Girl()//这个是你原来的 Girl类的析构 改成下边这样
~Girl()
{

}