1.catch子句参数为对象
先看一段代码:
#include <iostream> #include <exception> using namespace std; class MyException :public exception{ public: MyException(){ cout<<"MyException()"<<endl; } ~MyException(){ cout<<"~MyException()"<<endl; } MyException(const MyException& rhs){ cout<<"MyException(const MyException& rhs)"<<endl; } void what(){ cout<<"MyException what()"<<endl; } }; class DerivedException:public MyException{ public: DerivedException(){ cout<<"DerivedException()"<<endl; } ~DerivedException(){ cout<<"~DerivedException()"<<endl; } //派生类如果不显示调用基类的拷贝构造函数,则会隐式得调用基类的默认构造函数 DerivedException(const DerivedException& rhs):MyException(rhs){ cout<<"DerivedException(const DerivedException& rhs)"<<endl; } void what(){ cout<<"DerivedException what()"<<endl; } }; void ExceptionTest(){ try{ throw DerivedException();//这不是一个局部对象,并不会随着ExceptionTest()的退栈而销毁 }catch(MyException ex){ ex.what(); throw; //重新抛出的是原来的异常对象;没有更改过的。 } } int main(){ try{ ExceptionTest(); }catch(DerivedException ex){ ex.what(); } return 0; }
程序运行结果:
2.当catch子句为引用参数
代码如下:
#include <iostream> #include <exception> using namespace std; class MyException :public exception{ public: MyException(){ cout<<"MyException()"<<endl; } ~MyException(){ cout<<"~MyException()"<<endl; } MyException(const MyException& rhs){ cout<<"MyException(const MyException& rhs)"<<endl; } void what(){ cout<<"MyException what()"<<endl; } }; class DerivedException:public MyException{ public: DerivedException(){ cout<<"DerivedException()"<<endl; } ~DerivedException(){ cout<<"~DerivedException()"<<endl; } //派生类如果不显示调用基类的拷贝构造函数,则会隐式得调用基类的默认构造函数 DerivedException(const DerivedException& rhs):MyException(rhs){ cout<<"DerivedException(const DerivedException& rhs)"<<endl; } void what(){ cout<<"DerivedException what()"<<endl; } }; void ExceptionTest(){ try{ throw DerivedException();//这不是一个局部对象,并不会随着ExceptionTest()的退栈而销毁 }catch(MyException &ex){ ex.what(); throw; //如果对ex做出改变,则改变会被繁殖到下一个catch子句中 } } int main(){ try{ ExceptionTest(); }catch(DerivedException &ex){ ex.what(); } return 0; }
程序运行结果如下:
时间: 2024-10-11 03:00:28