C++ - 异常类(exception classes) 的 详解 及 代码

C++ - 异常类(exception classes) 的 详解 及 代码

本文地址: http://blog.csdn.net/caroline_wendy/article/details/17498665

异常类(exception classes)包含4种基类,bad_cast, bad_alloc,runtime_error, logic_error;

runtime_error: 错误只有当程序运行时, 才能检测出来;

logic_error: 应用程序检测出的逻辑错误.

其中bad_cast, bad_alloc使用默认构造器, runtime_error, logic_error, 必须使用string(C-style或stl)进行初始化;

用户定义的类也可以继承(inherit)自异常类, 并初始化相应的参数;

代码如下:

/*  * cppprimer.cpp  *  *  Created on: 2013.11.28  *      Author: Caroline  */  /*eclipse cdt, gcc 4.8.1*/  /* setlocale example */ #include <iostream> #include <string> #include <stdexcept>  using namespace std;  class out_of_stock : public std::runtime_error { public: 	//初始化基类的runtime_error 	explicit out_of_stock(const std::string &s) : std::runtime_error(s) {} };  class id_mismatch : public std::logic_error { public: 	explicit id_mismatch(const std::string &s) : std::logic_error(s) {} 	id_mismatch(const std::string &s, const std::string &lhs, const std::string &rhs) : 		std::logic_error(s), left(lhs), right(rhs) {} 	const std::string left, right; };  struct My_food { 	My_food(const std::string fi, const int fn) : food_id(fi), food_num(fn) {} 	My_food& operator+=(const My_food& rhs); 	std::string food_id; 	int food_num; };  My_food& My_food::operator+=(const My_food& rhs) { 	if(this->food_id != rhs.food_id) 		throw id_mismatch("wrong id", this->food_id, rhs.food_id); 	this->food_num += rhs.food_num; 	return *this; }  int main (void) { 	My_food M1("Apple", 3), M2("Pear", 2), M3("Apple", 2); 	try{ 		M1 += M3; 		std::cout << M1.food_id << ":" << M1.food_num << std::endl; 		M1 += M2; 	}catch(const id_mismatch &e){ 		std::cerr << e.what() << ": left id(" 				<< e.left <<") right id(" << e.right << ")" << std::endl; 	} } 

输出:

Apple:5 wrong id: left id(Apple) right id(Pear)