C++的異常類(exception classes) 詳解

異常類(exception classes)包含4種基類,bad_cast, bad_alloc,runtime_error, logic_error;

runtime_error: 錯誤只有當程序運行時, 才能檢測出來;

logic_error: 應用程序檢測出的邏輯錯誤.

其中bad_cast, bad_alloc使用默認構造器, runtime_error, logic_error, 必須使用string(C-style或stl)進行初始化;

用戶定義的類也可以繼承(inherit)自異常類, 並初始化相應的參數;

代碼如下:

/* 
 * 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:  
    //初始化基類的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;  
    }  
}

輸出:

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

作者：csdn博客 Spike_King