C++ 模板实现 智能指针

下面是C++模板实现的智能指针

 /**************************************************************** NAME : CSmartPtr.h* FUNCTION : 智能指针* PROGRAMMED : Ming_zhang* DATE(ORG) : Jun 02 2010* PROJECT : * OS : Windows XP* HISTORY : * ID --- DATE -----------NOTE-------------------------------* 00 ***************************************************************/#ifndef _CSMARTPTR_H_EFBAB248_67C2_4C3B_A146_FC03095EC3BA#define _CSMARTPTR_H_EFBAB248_67C2_4C3B_A146_FC03095EC3BAnamespace stm{template<typename T>class CSmartPtr{public:/*Constructor*/CSmartPtr();CSmartPtr(const T * ptr);CSmartPtr(const CSmartPtr<T> & ptr);/*Assignment Operators*/CSmartPtr<T> &operator =(T*ptr) ;CSmartPtr<T> &operator =(const CSmartPtr<T>& ptr) ;T* operator ->() throw(runtime_error);T& operator *() throw(runtime_error);/*const version*/T* const operator ->()const throw(runtime_error);const T& operator *()const throw(runtime_error);/*Destructors*/~CSmartPtr();private:int * _ptrCount;T * _ptr;};template<typename T>CSmartPtr<T>::CSmartPtr():_ptr(0),_ptrCount(0){}template<typename T>CSmartPtr<T>::CSmartPtr(const T * ptr):_ptr(ptr){if(_ptr!=NULL)/*防止参数为空*/{_ptrCount = new int(0);(*_ptrCount)++;}}template<typename T>CSmartPtr<T>::CSmartPtr(const CSmartPtr<T> & ptr):_ptr(0),_ptrCount(0){if(ptr._ptr!=0)/*防止参数为空指针*/{this->_ptr =ptr._ptr;this->_ptrCount = ptr._ptrCount;(*_ptrCount)++;}}template<typename T>CSmartPtr<T>::~CSmartPtr(){if(_ptr!=0){(*_ptrCount)--;if(*_ptrCount==0){delete _ptr;delete _ptrCount;}}}template<typename T>CSmartPtr<T> & CSmartPtr<T>::operator =( T * ptr) {if(ptr != this->_ptr){//防止自我赋值if(_ptr==NULL){//自己为空if(ptr!=NULL)//参数不为空{_ptrCount = new int(0);(*_ptrCount)++;_ptr = ptr;}else//参数为空{}}else{//自己不为空(*_ptrCount)--;if(*_ptrCount==0){/*释放 _ptr */delete _ptr;}_ptr = ptr;*_ptrCount = 1;}}return *this;}template<typename T>CSmartPtr<T> & CSmartPtr<T>::operator =(const CSmartPtr<T> &ptr) {if(ptr._ptr!=_ptr){//防止自我赋值if(ptr._ptr==0){// 参数为空if(_ptr!=0){//自己不为空(*_ptrCount)--;if(*_ptrCount==0){//释放自己原来指向的空间delete _ptr;delete _ptrCount;}_ptr = ptr._ptr;_ptrCount=ptr._ptrCount;}else{//自己为空 什么都不做}}else{// 参数不为空if(_ptr!=0){//自已不为空(*_ptrCount)--;if(*_ptrCount==0){//释放自己原来指向的空间delete _ptr;delete _ptrCount;}}_ptr = ptr._ptr;_ptrCount = ptr._ptrCount;(*_ptrCount)++;}}return *this;}template<typename T>T* CSmartPtr<T>::operator ->() throw(runtime_error){if(_ptr!=0)return _ptr;throw runtime_error("access through NULL pointer");}template<typename T>T& CSmartPtr<T>::operator *() throw(runtime_error){if(_ptr!=0)return *_ptr;throw std::runtime_error("dereference of NULL pointer");}template<typename T>T* const CSmartPtr<T>::operator ->()const throw(runtime_error){if(_ptr!=0)return _ptr;throw runtime_error("access through NULL pointer");}template<typename T>const T& CSmartPtr<T>::operator *()const throw(runtime_error){if(_ptr!=0)return *_ptr;throw std::runtime_error("dereference of NULL pointer");}}//namespace stm#endif //_CSMARTPTR_H_EFBAB248_67C2_4C3B_A146_FC03095EC3BA