C++ – 异常类(exception classes) 的详解及代码

孤风一剑 12月 23, 2013 249 0

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:

[cpp][/cpp] view plaincopy

/*
* 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:

[plain][/plain] view plaincopy

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