3 try块和异常处理 throw catch

#include<iostream> //包含头文件
#include <stdlib.h>//exit

using std::endl;
using std::cout;
using std::cerr;

double fuc(double x, double y) //定义函数
{
    if(y==0)
    {
        throw y; //除数为0，抛出异常
    }
    return x/y; //否则返回两个数的商
}

int main()
{
    double res;
    try //定义异常
    {
        res=fuc(2,3);
        cout<<"The result of x/y is : "<<res<<endl;
        res=fuc(4,0); //出现异常 //抛出 double 类型异常
    }
    catch(double) //捕获并处理异常
    {
        cerr<<"error of dividing zero.\n";
        exit(1); //异常退出程序
    }
    exit(0);
}

ywx@ywx:~/yu/c++_4th/6$ ./exception
The result of x/y is : 0.666667
error of dividing zero.

#include<iostream>
#include <string>

using namespace std;

class Person
{
private:
    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;
}

ywx@ywx:~/yu/c++_4th/6$ ./exception
name is error
hello world