//第2點(diǎn)
T& operator[](int index)
{
	//問題: 當(dāng)訪問的下標(biāo)index超出容器的范圍，此時(shí)該返回什么值?
    //解決方案: 可以再傳一個(gè)參數(shù)，用于獲取真正的結(jié)果(當(dāng)輸出型參數(shù)), 返回值就用于判斷是否正確的返回了. 
    //實(shí)際上還是很麻煩
}

try
{
    //保護(hù)代碼(可能會(huì)拋出異常的代碼)
}catch(ExceptionType e1)
{
    //處理異常
}catch(ExceptionType e2)
{
    //處理異常
}catch(ExceptionType eN)
{
    //處理異常
}

//代碼演示：f3()中拋出異常，該異常會(huì)被f1()捕捉，而在main函數(shù)中的catch是無法捕捉到的
void f3()
{
	throw 123;
}
void f2()
{
    f3();
}
void f1()
{
    try
    {
        f2();
        cout << "f1() not catched Exception!" << endl;
    }catch(int& err)
    {
        cout << "f1()-err: " << err << endl;
    }
}

int main()
{
    try
    {
        f1();
        cout << "main not catched Exception!" << endl;
    }catch(int& err)
    {
        cout << "main-err: " << err << endl; 
    }
    return 0;
}

//在SecondThrowException()函數(shù)中我們要delete[]動(dòng)態(tài)開辟(new出來)的空間，
//如果不使用異常的重新拋出的話，就會(huì)造成內(nèi)存泄漏問題 (也可以使用RAII)
void FirstThrowException()
{
    throw "First throw a exception!";
}

void SecondThrowException()
{
    int* arr = new int[10];
    try
    {
        FirstThrowException();
    }catch(...)
    {
        cout << "Delete[] arr Success!" << endl;
        delete[] arr;
        throw;
    }
}

void SoluteException()
{
    try
    {
        SecondThrowException();
    }catch(const char* err)
    {
        cout << err << endl;
    }
}

int main()
{
    SoluteException();
    return 0;
}

class MyException
{
public:
	MyException(string errmsg, int id)
		:_errmsg(errmsg),
		 _id(id)
	{}
	
	virtual string what() const = 0;	//必須放到public下才能讓類外定義的成員訪問到
protected:
	int _id;		//錯(cuò)誤碼
	string _errmsg;	//存放錯(cuò)誤信息
	//list<StackInfo> _traceStack;	//存放調(diào)用鏈的信息
    //...
};

class CacheException : public MyException
{
public:
	CacheException(string errmsg, int id)
		:MyException(errmsg, id)
	{}

	virtual string what() const
	{
		return "CacheException!: " + _errmsg;
	}
};

class NetworkException : public MyException
{
public:
	NetworkException(string errmsg, int id)
		:MyException(errmsg, id)
	{}

	virtual string what() const
	{
		return "NetworkException!: " + _errmsg;
	}
};

class SqlException : public MyException
{
public:
	SqlException(string errmsg, int id)
		:MyException(errmsg, id)
	{}

	virtual string what() const
	{
		return "SqlException!: " + _errmsg;
	}
};

int main()
{
	try
	{
		//拋出任意的派生類對(duì)象
		throw SqlException("sql open failed", 10);
	}
    catch (const MyException& e)	//只需要捕獲基類對(duì)象
	{
		cout << e.what() << endl;	//這里實(shí)際上完成了一個(gè)多態(tài)
	}
	catch (...)	//走到這里說明出現(xiàn)未知異常
	{
		cout << "Unknown Exception!" << endl;
	}

	return 0;
}

void func1() throw(); //表示該函數(shù)不會(huì)拋異常
void func2() noexcept; //等價(jià)于throw()  表示該函數(shù)不會(huì)拋異常
void func3() throw(std::bad_alloc);	//表示該函數(shù)只會(huì)拋出bad_alloc的異常
void func4() throw(int, double, string); //表示該函數(shù)會(huì)拋出int/double/string類型中的某種異常

int main()
{
	try
    {
        vector<int> v(5);
        v.at(5) = 0;	//v.at(下標(biāo)) = v[下標(biāo)] + 拋異常
    }
    catch(const exception& e)
    {
        cout << e.what() << endl;
    }
    catch(...)
    {
		cout << "Unknown Exception!" << endl;        
    }
}