C++内置了异常处理的语法元素try.....catch.....
1.try语句处理正常代码逻辑
2.catch语句处理异常情况
3.try语句中的异常由对应的catch语句处理
常见的语句如下

try{ double r=divide(1,0);}catch(...){ cout<<"the result..."<<endl;}

C++通过throw语句抛出异常信息

double divide(double a,double b){ const double delta=0.00000000001; double ret=0; if(!((-delta<b)&&(b<delta))) { ret=a/b; } else { throw 0;//产生除0异常 } return ret;}

C++异常处理分析
throw抛出的异常必须被catch处理--当前函数能够处理异常，程序机械往下执行，当前函数无法处理异常，则函数停止执行，并返回.未被处理的异常会顺着函数调用栈向上传播，直到被处理为止，否则程序将停止执行

//代码示例#include <iostream>using namespace std;double divide(double a, double b){ const double delta = 0.000000000000001; double ret = 0; if( !((-delta < b) && (b < delta)) ) { ret = a / b; } else { throw 0; // 产生除 0 异常 } return ret;}void Demo1(){ try { throw 'c'; } catch(int i) { cout << "catch(int i)" << endl; } catch(double d) { cout << "catch(double d)" << endl; } catch(char c) { cout << "catch(char c)" << endl; }}void Demo2(){ throw 0.0001; // "D.T.Software"; // const char*}int main(){ cout << "main() begin" << endl; try { double c = divide(1, 1); cout << "c = " << c << endl; } catch(...) { cout << "Divided by zero..." << endl; } Demo1(); try { Demo2(); } catch(char* c) { cout << "catch(char* c)" << endl; } catch(const char* cc) { cout << "catch(char* cc)" << endl; } catch(...) { cout << "catch(...)" << endl; } cout << "main() end" << endl; return 0;}二 异常类的构建

异常的类型可以是自定义类类型，对于类类型异常的匹配依旧是至上而下严格匹配，赋值兼容性原则在异常匹配中依然适用
异常类的功能定义

#ifndef EXCEPTION_H#define EXCEPTION_H/* 异常的类型可以是自定义类类型 对于类类型异常的匹配依旧是至上而下严格匹配 一般而言 匹配子类异常的catch放在上部 匹配父类异常的catch放在下部 */#include "Object.h"namespace MyLib{//定义宏THROW_EXCEPTION，抛出异常时直接写异常类型及异常信息即可#define THROW_EXCEPTION(e, m) (throw e(m, __FILE__, __LINE__)) class Exception:public Object { protected: char* m_message;//异常的信息 char* m_location;//异常的位置 void init(const char* message,const char *file,int line); public: Exception(const char* message); Exception(const char *file,int line); Exception(const char* message,const char *file,int line); Exception(const Exception& e); Exception& operator=(const Exception& e); virtual const char* message()const; virtual const char* location()const; virtual ~Exception();//纯虚函数 }; class ArithmeticException : public Exception { public: ArithmeticException():Exception(0){} ArithmeticException(const char* message):Exception(message){} ArithmeticException(const char* file,int line):Exception(file,line){} ArithmeticException(const char*message,const char*file,int line):Exception(message,file,line){} ArithmeticException(const ArithmeticException& e):Exception(e){}//拷贝构造函数 ArithmeticException&operator =(const ArithmeticException& e) { Exception::operator =(e); return *this; } }; class NullPointerException : public Exception { public: NullPointerException():Exception(0){} NullPointerException(const char* message):Exception(message){} NullPointerException(const char* file,int line):Exception(file,line){} NullPointerException(const char*message,const char*file,int line):Exception(message,file,line){} NullPointerException(const NullPointerException& e):Exception(e){}//拷贝构造函数 NullPointerException&operator =(const NullPointerException& e) { Exception::operator =(e); return *this; } }; class indexOutOfBoundsException : public Exception { public: indexOutOfBoundsException():Exception(0){} indexOutOfBoundsException(const char* message):Exception(message){} indexOutOfBoundsException(const char* file,int line):Exception(file,line){} indexOutOfBoundsException(const char*message,const char*file,int line):Exception(message,file,line){} indexOutOfBoundsException(const indexOutOfBoundsException& e):Exception(e){}//拷贝构造函数 indexOutOfBoundsException&operator =(const indexOutOfBoundsException& e) { Exception::operator =(e); return *this; } }; class NoEoughMemoryException : public Exception { public: NoEoughMemoryException():Exception(0){} NoEoughMemoryException(const char* message):Exception(message){} NoEoughMemoryException(const char* file,int line):Exception(file,line){} NoEoughMemoryException(const char*message,const char*file,int line):Exception(message,file,line){} NoEoughMemoryException(const NoEoughMemoryException& e):Exception(e){}//拷贝构造函数 NoEoughMemoryException&operator =(const NoEoughMemoryException& e) { Exception::operator =(e); return *this; } }; class InvalidOperationException : public Exception { public: InvalidOperationException():Exception(0){} InvalidOperationException(const char* message):Exception(message){} InvalidOperationException(const char* file,int line):Exception(file,line){} InvalidOperationException(const char*message,const char*file,int line):Exception(message,file,line){} InvalidOperationException(const InvalidOperationException& e):Exception(e){}//拷贝构造函数 InvalidOperationException&operator =(const InvalidOperationException& e) { Exception::operator =(e); return *this; } }; class InvalidParameterException : public Exception { public: InvalidParameterException():Exception(0){} InvalidParameterException(const char* message):Exception(message){} InvalidParameterException(const char* file,int line):Exception(file,line){} InvalidParameterException(const char*message,const char*file,int line):Exception(message,file,line){} InvalidParameterException(const InvalidParameterException& e):Exception(e){}//拷贝构造函数 InvalidParameterException&operator =(const InvalidParameterException& e) { Exception::operator =(e); return *this; } };}#endif // EXCEPTION_H

三 顶层父类的创建
创建顶层父类的意义--遵循经典设计准则，所有的数据都继承Object类，定义动态内存申请的行为，提高代码的移植性
顶层父类的接口定义

class Object { public: void* operator new(unsigned int size)throw(); void operator delete(void* p); void* operator new[](unsigned int size)throw(); void operator delete[](void* p); ~Object(); }; /* Object类是所写的顶层父类 Object类用于统一内存申请的行为 在堆中创建Object子类的对象，失败时返回NULL值 Object类为纯虚父类，所有子类都能进行动态类型识别 */