分类: C/C++
2008-04-23 21:41:19
OLE字符串
作者:
一、概述
32位宽字符串,前面32位为长度,尾部以0结束
二、相关定义
BSTR (又称Basic 类型字符串)
LPOLESTR
相关宏定义:
typedef unsigned short wchar_t; (unsigned short为两字节) typedef wchar_t WCHAR; typedef WCHAR OLECHAR; (Win32) typedef OLECHAR* BSTR; typedef /* [string] */ OLECHAR __RPC_FAR *LPOLESTR;
三、使用
1.分配
// Create BSTR containing "Text" bs = SysAllocString(L"Text") // Create BSTR containing "Te" bs = SysAllocStringLen(L"Text", 2) // Create BSTR containing "Text" followed by \0 and a junk character bs = SysAllocStringLen(L"Text", 6) // Reallocate BSTR bs as "NewText" 重新赋值 f = SysReAllocString(&bs, "NewText");
2.长度
// Get character length of string. cch = SysStringLen(bs);
3.释放
// Deallocate a string. SysFreeString(bs);
四、转换问题
1 使用_bstr_t
BSTR tmpBStr; m_pObject1->get_ObjectString(&tmpBStr); _bstr_t tmpbstr(tmpBStr, FALSE); //将得到的BSTR作为构造函数参数 SetDlgItemText(IDC_CURPROPVAL, tmpbstr);
注意: 直接赋值转换,会引发内存泄漏
BSTR tmpBStr; m_pObject1->get_ObjectString(&tmpBStr); _bstr_t tmpbstr; tmpbstr= tmpBStr; //Caution: 内存泄漏参数 SetDlgItemText(IDC_CURPROPVAL, tmpbstr);
2 使用T2COLE、T2OLE等
#include <afxpriv.h>
在转换前需要添加宏
USES_CONVERSION
#define USES_CONVERSION int _convert = 0; \ _convert;\ UINT _acp = GetACP();\ _acp;\ LPCWSTR _lpw = NULL;\ _lpw;\ LPCSTR _lpa = NULL;\ _lpa
这个宏提供了一些临时变量供转化用
看一下其在单字节字符集时的宏定义
#define T2COLE(lpa) A2CW(lpa) #define T2OLE(lpa) A2W(lpa) #define OLE2CT(lpo) W2CA(lpo) #define OLE2T(lpo) W2A(lpo) #define A2CW(lpa) ((LPCWSTR)A2W(lpa)) #define W2CA(lpw) ((LPCSTR)W2A(lpw)) #define A2W(lpa) (\ ((_lpa = lpa) == NULL) ? NULL : (\ _convert = (lstrlenA(_lpa) 1),\ ATLA2WHELPER((LPWSTR) alloca(_convert*2), _lpa, _convert))) #define W2A(lpw) (\ ((_lpw = lpw) == NULL) ? NULL : (\ _convert = (lstrlenW(_lpw) 1)*2,\ ATLW2AHELPER((LPSTR) alloca(_convert), _lpw, _convert))) LPSTR AFXAPI AfxW2AHelper(LPSTR lpa, LPCWSTR lpw, int nChars) { if (lpw == NULL) return NULL; ASSERT(lpa != NULL); // verify that no illegal character present // since lpa was allocated based on the size of lpw // don''t worry about the number of chars lpa[0] = ''\0''; VERIFY(WideCharToMultiByte(CP_ACP, 0, lpw, -1, lpa, nChars, NULL, NULL)); return lpa; } LPWSTR AFXAPI AfxA2WHelper(LPWSTR lpw, LPCSTR lpa, int nChars) { if (lpa == NULL) return NULL; ASSERT(lpw != NULL); // verify that no illegal character present // since lpw was allocated based on the size of lpa // don''t worry about the number of chars lpw[0] = ''\0''; VERIFY(MultiByteToWideChar(CP_ACP, 0, lpa, -1, lpw, nChars)); return lpw; }
3 .CString 对转化的支持
//m_cstrCaption是一个CString 对象。 BSTR bstrCaption =m_cstrCaption.AllocSysString(); FireChange(&bstrCaption,&m_lAlignment); ::SysFreeString(bstrCaption);(全文完)