自己写的share_ptr + Arry 来制作CString共享版本
#include "MyStudyFile.h"#include <crtdbg.h>#include <boost/smart_ptr/shared_ptr.hpp>int strlength (const char * str){const char *eos = str;while( *eos++ ) ;return( eos - str - 1 );}char * strcapend (char * dst,const char * src){char * cp = dst;while( *cp )cp++;while( *cp++ = *src++ ) ;return( dst );}char * __cdecl strcopy(char * dst, const char * src){char * cp = dst;while( *cp++ = *src++ );return( dst );}template<class T>void SwapFun(T& left, T& right){T temp = left;left = right;right = temp;}template<class T>class CArry{typedef T ELEMENT_TYPE;public:CArry(const ELEMENT_TYPE* pChar, int nSize):m_iMaxSize(nSize), m_iCurentSize(nSize){m_pVChar = new ELEMENT_TYPE[m_iMaxSize];ELEMENT_TYPE* pStart = m_pVChar;while (nSize --){*pStart++ = *pChar++;}}CArry(const ELEMENT_TYPE* pChar, int nSize, int nMaxSize):m_iMaxSize(nMaxSize), m_iCurentSize(nSize){m_pVChar = new ELEMENT_TYPE[m_iMaxSize];ELEMENT_TYPE* pStart = m_pVChar;while (nSize --){*pStart++ = *pChar++;}}CArry& Append(const ELEMENT_TYPE* pChar, int nSize){if (nSize + m_iCurentSize <= m_iMaxSize){ELEMENT_TYPE* pStart = m_pVChar+ m_iCurentSize;while(nSize --){*pStart++ = *pChar++;}}else{CArry(m_pVChar, m_iCurentSize, nSize + m_iCurentSize).Swap(this);Append(pChar, nSize);}}CArry& Assign(const int posAfter, ELEMENT_TYPE* pChar, int nSize){ELEMENT_TYPE* pStart = m_pVChar + posAfter;while(nSize --){*pStart++ = *pChar++;}}~CArry(){delete[] m_pVChar;}operator ELEMENT_TYPE*(){return m_pVChar;}int GetSize(){return m_iCurentSize;}private:void Swap(CArry& other){SwapFun(m_pVChar, other.m_pVChar) ;SwapFun(m_iMaxSize, other.m_iMaxSize);SwapFun(m_iCurentSize, other.m_iCurentSize);}ELEMENT_TYPE* m_pVChar;int m_iMaxSize;int m_iCurentSize;};//共享的实现。template<class T>class ShareDataImp{typedef T ElementType;private:struct SharedData{SharedData(ElementType* p = NULL):m_p(p), nRef(1){}void AddRef(){++ nRef;}void Release(){if (-- nRef == 0){delete m_p;m_p = NULL;}}ElementType* GetPtr(){return m_p;}int GetCount(){return nRef;}private:ElementType* m_p;int nRef;};public:ShareDataImp(ElementType* pstr = NULL) : m_pData(new SharedData(pstr)){}~ShareDataImp(){m_pData->Release();if (m_pData->GetCount() == 0){delete m_pData;}m_pData = NULL;}ShareDataImp(const ShareDataImp& _right): m_pData(_right.m_pData){m_pData->AddRef();}//释放对共享数据的所有权。void ResetAs(ElementType* p){m_pData->Release();delete m_pData;m_pData = new SharedData(p);}ElementType* Get() const{return m_pData->GetPtr();}private:SharedData* m_pData;};class CString{public:CString(char* pStr){CArry<char>* pArry = new CArry<char>(pStr, strlength(pStr) + 1);m_shareData.ResetAs(pArry);}~CString(){}const char* cstr() const{ return *(m_shareData.Get());}CString& Append(CString& strVal){CString strRight(strVal.cstr());m_shareData.ResetAs(CloneData(GetLength() + strRight.GetLength() + 1));m_shareData.Get()->Assign(GetLength(), strRight.cstr(), strRight.GetLength() + 1);return *this;}CString& Append(char* pChar, int iLength){m_shareData.ResetAs(CloneData(GetLength() + iLength + 1));m_shareData.Get()->Assign(GetLength(), pChar, iLength + 1);}CString& Assign(const CString& strVal){m_shareData.ResetAs(strVal.CloneData(strVal.GetLength() + 1));return *this;}CString& Assign(char* pStr){m_shareData.ResetAs(new CArry<char>(pStr, strlength(pStr) + 1));return *this;}int GetLength() const{return m_shareData.Get()->GetSize() - 1;}private:char* cstr(){return *(m_shareData.Get());}CArry<char>* CloneData(int iSize) const{return new CArry<char>(cstr(), GetLength() + 1, iSize);}ShareDataImp<CArry<char>> m_shareData;};int main(){CString* pVal = new CString("121312");CString* pVa2 = new CString(*pVal);CString* pVa3 = new CString(*pVa2);CString* pVa4 = new CString(*pVa3);delete pVal;delete pVa2;delete pVa3;delete pVa4;_CrtDumpMemoryLeaks();}?