C++ operator 的超棒demo

ゞ浴缸里的玫瑰 2022-02-03 22:47 264阅读 0赞

class CStrPtr {
    	LPTSTR m_szStr;
    public:
    	// A collection of constructors.
    	CStrPtr();
    	CStrPtr(int iSiz);
    	CStrPtr(CStrPtr& utStr);
    	CStrPtr(LPCTSTR szStr);
    
    	~CStrPtr();			
    	//类型转换的操作符写法,可以看到返回值都在 operator 的后面
    	operator LPTSTR();							
    	operator LPCTSTR();
    	operator BYTE *();
    	
    	//赋值等操作符的写法,可以看到返回值都在 operator 的前面
    	CStrPtr& operator= (LPCTSTR szStr);			
    	CStrPtr& operator= (CStrPtr& utStr);		
    	CStrPtr& operator+ (CStrPtr& utStr);
    	
    	LPTSTR Ptr();
    };

CStrPtr::CStrPtr() {
    	m_szStr = NULL;
    }
    
    CStrPtr::CStrPtr(int iSiz) {
        m_szStr = NULL;
    	if (iSiz) {
    		m_szStr = new TCHAR[iSiz];
            ASSPTR(m_szStr);
    	}
    }
    
    CStrPtr::CStrPtr(CStrPtr& utStr) {
    	m_szStr = NULL;
    	*this = utStr;
    }
    
    CStrPtr::CStrPtr(LPCTSTR szStr) {
    	m_szStr = NULL;
    	*this = szStr;
    }
    
    CStrPtr::~CStrPtr() {
    	if (m_szStr != NULL) delete m_szStr;
    }
    
    CStrPtr::operator LPTSTR() {
    	return m_szStr;
    }
    
    CStrPtr::operator LPCTSTR() {
    	return m_szStr;
    }
    
    CStrPtr::operator BYTE *() {
    	return (BYTE *)m_szStr;
    }
    
    CStrPtr&
    CStrPtr::operator= (LPCTSTR szStr) {
    	if (m_szStr != NULL) delete m_szStr;
    	if (szStr != NULL) {
            size_t ccStr = _tcslen(szStr) + 1;
    		m_szStr = new TCHAR[ccStr];
            ASSPTR(m_szStr);
    
            _tcscpy_s(m_szStr, ccStr, szStr);
    	} else {
    		m_szStr = NULL;
    	}
    	return *this;
    }
    
    CStrPtr&
    CStrPtr::operator= (CStrPtr& utStr) {
    	return *this = (LPTSTR)utStr;
    }
    
    CStrPtr&
    CStrPtr::operator +(CStrPtr& utStr) {
        size_t ccNew = _tcslen(m_szStr) + _tcslen(utStr.m_szStr) + 1;
    	LPTSTR szNew = new TCHAR[ccNew];
        ASSPTR(m_szStr);
    
        _tcscpy_s(szNew, ccNew, m_szStr);
        _tcscat_s(szNew, ccNew, utStr.m_szStr);
    	delete[] m_szStr;
    	m_szStr = szNew;
    	return *this;
    }
    
    LPTSTR
    CStrPtr::Ptr() {
    	LPTSTR szTmp = m_szStr;
    	m_szStr = NULL;
    	return szTmp;
    }