C++ throw catch try方法

#include<iostream>
#include <string>
using namespace std;
class Person
{
int age;
string name;
public:
void setAge(int);
void setName(string);
};
class Error
{
public:
virtual void show()=0;
};
class nameError:public Error
{
public:
void show() { cout<<"name is error"<<endl; }
};
class ageError:public Error
{
public:
void show() { cout<<"age is error"<<endl; }
};
void Person::setAge(int a)
{
ageError ag;
if(a<0||a>100) throw ag;
this->age=a;
}
void Person::setName(string str)
{
nameError ne;
if(str=="exit") throw ne;
this->name=str;
}

int main(void)
{
Person p;
try
{
p.setAge(0);
p.setName("exit");
}
catch(Error &er)
{
er.show();
}
cout<<"hello world"<<endl;
return 0;
}