c++ 异常处理

#include "stdafx.h"
#include <iostream>
using namespace std;

enum EHstate{ noErr, zeroOP,nega, severeError};
enum EHstate state = noErr;
int mathFunc(int i)
{
    if(i == 0)
    {
        throw state;
    }
}
void calculate(int op)
{
    try
    {
        mathFunc(op);
    }
    catch(EHstate &eobj)//声明为引用
    {
        eobj = severeError;//此处未修改全局变量的值
    }
}
int _tmain(int argc, _TCHAR* argv[])
{
    cout<<"全局变量："<<state<<endl;
    calculate(0);
    cout<<"全局变量："<<state<<endl;
    return 0;
}


#include "stdafx.h"
#include <iostream>
using namespace std;

enum EHstate{ noErr, zeroOP,nega, severeError};
enum EHstate state = noErr;
int mathFunc(int i)
{
    if(i == 0)
    {
        throw state;
    }
}
void calculate(int op)
{
    try
    {
        mathFunc(op);
    }
    catch(EHstate eobj)//此处为对象，不是引用
    {
        eobj = severeError;//修改此局部对象
        throw;//抛出的仍然是原始的异常对象，而非修改的局部对象
    }
}
int _tmain(int argc, _TCHAR* argv[])
{
    cout<<"全局变量："<<state<<endl;
    try
    {
        calculate(0);
    }
    catch(EHstate eobj)
    {
        cout<<"捕捉的异常对象值："<<eobj<<endl;
    }
    cout<<"全局变量："<<state<<endl;
    return 0;
}