C ++ templates implement smart pointers

The following is the smart pointer implemented by the C ++ template.

 /*************************************** * ********************** <Br/> * Name: csmartptr. h <br/> * function: smart pointer <br/> * programmed: ming_zhang <br/> * Date (org): Jun 02 2010 <br/> * Project: <br/> * OS: Windows XP <br/> * history: <br/> * ID --- date ----------- note --------------------------- <br/> * 00 <br/> ******************* **************************************** * ***/</P> <p> # ifndef _ csmartp Tr_h_efbab248_67c2_4c3b_a146_fc03095ec3ba <br/> # DEFINE _ attributes </P> <p> namespace STM <br/>{</P> <p> template <typename T> <br/> class csmartptr <br/>{< br/> public: <br/>/* constructor */<br/> csmartptr (); <br/> csmartptr (const T * PTR ); <br/> csmartptr (const csmartptr <t> & PTR ); <br/>/* assignment operators */<br/> csmartptr <t> & operator = (T * PTR); <br/> csmartptr <t> & Operator = (const csmartptr <t> & PTR); </P> <p> T * operator-> () Throw (runtime_error ); <br/> T & operator * () Throw (runtime_error); <br/>/* const version */<br/> T * const operator-> () const throw (runtime_error); <br/> const T & operator * () const throw (runtime_error); <br/>/* Destructors */<br/> ~ Csmartptr (); <br/> PRIVATE: <br/> int * _ ptrcount; <br/> T * _ PTR; <br/> }; </P> <p> template <typename T> <br/> csmartptr <t>: csmartptr (): _ PTR (0), _ ptrcount (0) <br/>{< br/>}</P> <p> template <typename T> <br/> csmartptr <t>: csmartptr (const T * PTR ): _ PTR (PTR) <br/>{< br/> If (_ PTR! = NULL)/* prevent the parameter from being null */<br/>{< br/> _ ptrcount = new int (0); <br/> (* _ ptrcount) ++; <br/>}</P> <p> template <typename T> <br/> csmartptr <t> :: csmartptr (const csmartptr <t> & PTR): _ PTR (0), _ ptrcount (0) <br/>{< br/> If (PTR. _ PTR! = 0)/* prevent the parameter from being a null pointer */<br/>{< br/> This-> _ PTR = PTR. _ PTR; <br/> This-> _ ptrcount = PTR. _ ptrcount; <br/> (* _ ptrcount) ++; <br/>}< br/> template <typename T> <br/> csmartptr <t> ::~ Csmartptr () <br/>{< br/> If (_ PTR! = 0) <br/>{< br/> (* _ ptrcount) --; <br/> If (* _ ptrcount = 0) <br/>{< br/> Delete _ PTR; <br/> Delete _ ptrcount; <br/>}</P> <p> template <typename T> <br/> csmartptr <t> & csmartptr <t>:: Operator = (T * PTR) <br/>{< br/> If (PTR! = This-> _ PTR) <br/> {// prevent self-assignment <br/> If (_ PTR = NULL) <br/> {// empty <br/> If (PTR! = NULL) // The parameter is not null <br/>{< br/> _ ptrcount = new int (0); <br/> (* _ ptrcount) ++; <br/> _ PTR = PTR; <br/>}< br/> else // The parameter is null <br/>{< br/>}< br/> else <br/> {// you are not empty. <br/> (* _ ptrcount) --; <br/> If (* _ ptrcount = 0) <br/> {/* release _ PTR */<br/> Delete _ PTR; <br/>}< br/> _ PTR = PTR; <br/> * _ ptrcount = 1; <br/>}< br/> return * this; <br/>}</P> <p> template <typename T> <br/> csmartptr <t> & csmartptr <t>: Operator = (const C Smartptr <t> & PTR) <br/> {<br/> If (PTR. _ PTR! = _ PTR) <br/>{// prevent self-assignment <br/> If (PTR. _ PTR = 0) <br/>{// the parameter is null <br/> If (_ PTR! = 0) <br/> {// you are not empty <br/> (* _ ptrcount) --; <br/> If (* _ ptrcount = 0) <br/> {// release the space originally pointed to <br/> Delete _ PTR; <br/> Delete _ ptrcount; <br/>}< br/> _ PTR = PTR. _ PTR; <br/> _ ptrcount = PTR. _ ptrcount; <br/>}< br/> else <br/>{// do nothing if you are empty <br/>}< br/> else <br />{// the parameter is not blank <br/> If (_ PTR! = 0) <br/> {// It is not empty <br/> (* _ ptrcount) --; <br/> If (* _ ptrcount = 0) <br/> {// release the space originally pointed to <br/> Delete _ PTR; <br/> Delete _ ptrcount; <br/>}< br/> _ PTR = PTR. _ PTR; <br/> _ ptrcount = PTR. _ ptrcount; <br/> (* _ ptrcount) ++; <br/>}< br/> return * this; <br/>}</P> <p> template <typename T> <br/> T * csmartptr <t >:: operator-> () Throw (runtime_error) <br/>{< br/> If (_ PTR! = 0) <br/> return _ PTR; <br/> throw runtime_error ("access through Null Pointer "); <br/>}</P> <p> template <typename T> <br/> T & csmartptr <t>: Operator * () Throw (runtime_error) <br/>{< br/> If (_ PTR! = 0) <br/> return * _ PTR; <br/> throw STD: runtime_error ("dereference of Null Pointer "); <br/>}</P> <p> template <typename T> <br/> T * const csmartptr <t >:: operator-> () const throw (runtime_error) <br/>{< br/> If (_ PTR! = 0) <br/> return _ PTR; <br/> throw runtime_error ("access through Null Pointer "); <br/>}< br/> template <typename T> <br/> const T & csmartptr <t>: Operator * () const throw (runtime_error) <br/>{< br/> If (_ PTR! = 0) <br/> return * _ PTR; <br/> throw STD: runtime_error ("dereference of Null Pointer "); <br/>}</P> <p >}// namespace STM <br/> # endif/_ csmartptr_h_efbab248_67c2_4c3b_a146_fc03095ec3ba