demo_exception_handling_4_b.cpp

对于一个初涉VC＋＋的人来书

//*******************************************************
// 演示在函数嵌套调用的情况下:异常逐层传递,检测处理异常.
//*******************************************************
// 在同级成对try-catch结构中:
// 异常信息被throw抛出(注意:可能在此时创建异常对象)后,
// 一旦被catch捕获,异常信息立即析构消失,随后处理异常,
// 或者将捕获到的异常再次抛出(注意:只能在在catch块中
// 捕获后,才能在该catch块中由throw再次抛出),到外一层
// try-catch结构中等待捕获处理.
// 若没有被catch捕获,则跳过try块随后语句,到外一层
// try-catch结构中等待类型匹配的catch捕获处理.
//*******************************************************

# include <iostream.h>

void trigger()
{
	cout<<"   begin of trigger()"<<endl;

	try
	{
		cout<<"   begin of try in trigger()"<<endl;
		cout<<"   throw exception in try"<<endl;
		throw "exception"; //引发char*类型的异常
		cout<<"   end of try in trigger()"<<endl;
	}

	catch(char message) //捕获char类型异常并作处理
	{
		cout<<"   begin of catch in trigger()"<<endl;
		cout<<"   catch "<<message<<" in trigger()"<<endl;
		cout<<"   end of catch in trigger()"<<endl;
	}

	cout<<"   end of trigger()"<<endl;

	return;
}

int main()
{
	cout<<"begin of main()"<<endl;

	//检测以下语句中的函数调用是否产生异常
	try
	{
		cout<<"try in main()"<<endl;
		trigger();
	}

	//捕获char*类型异常并作处理
	catch(char* message)
	{
		cout<<"catch "<<message<<" in main()"<<endl;;
	}
	
	cout<<"end of main()"<<endl;

	return 0;
}

/*
begin of main()
try in main()
   begin of trigger()
   begin of try in trigger()
   throw exception in try
catch exception in main()
end of main()
*/