http://www.vckbase.com/document/viewdoc/?id=1096
http://www.vckbase.com/document/viewdoc/?id=1082
CW2A(BSTR)
CW2A(_bstr_t)
CW2A(VARIANT.bstrVal)
CW2A(_varaint_t.bstrVal)
可以用宏W2T
void func( BSTR *lpsz )
{
USES_CONVERSION;
CString x = W2T(lpsz);
}
_variant_t var;
//把所有類型都轉(zhuǎn)成VT_BSTR
::VariantChangeType(&var,&var,0,VT_BSTR);
CString str=var.bstrVal;
用兩個函數(shù)就可以了：
轉(zhuǎn)string：_com_util::ConvertBSTRToString(BSTR pSrc);
轉(zhuǎn)BSTR: _com_util::ConvertStringToBSTR(const char *pSrc);
SES_CONVERSION;
OLE2T()
T2OLE()
//Create a BSTR and assign it to a Variant
BSTR x = SysAllocString(L"Hello");
VARIANT myVariant;
myVariant.vt = VT_BSTR;
myVariant.bstrVal = x;
SysFreeString(x);
//Create a CString and change it to a variant;
CString myCString(_T("My String"));
CString mySecondString;
//This is required to use the T2COLE macro.
USES_CONVERSION;
BSTR y = SysAllocString(T2COLE(myCString));
myVariant.bstrVal = y;
mySecondString = y;
SysFreeString(y);
_bstr_t str2="hjljljl";
char *str1 = (char*)str2;//char*是_bstr_t類的一個重載
CString str3=str1;
//Create two BSTRs and add them.
BSTR a = SysAllocString(L"One two ");
BSTR b = SysAllocString(L"three four.");
//or if CString already exists.
myCString = b;
BSTR bstr=L"afdjkl";
CString str=bstr;
BSTR bstr2=str.AllocSysString();
我們先定義一些常見類型變量借以說明
int i = 100;
long l = 2001;
float f=300.2;
double d=12345.119;
char username[]="女俠程佩君";
char temp[200];
char *buf;
CString str;
_variant_t v1;
_bstr_t v2;
一、其它數(shù)據(jù)類型轉(zhuǎn)換為字符串
短整型(int)
itoa(i,temp,10);///將i轉(zhuǎn)換為字符串放入temp中,最后一個數(shù)字表示十進(jìn)制
itoa(i,temp,2); ///按二進(jìn)制方式轉(zhuǎn)換
長整型(long)
ltoa(l,temp,10);
二、從其它包含字符串的變量中獲取指向該字符串的指針
CString變量
str = "2008北京奧運(yùn)";
buf = (LPSTR)(LPCTSTR)str;
BSTR類型的_variant_t變量
v1 = (_bstr_t)"程序員";
buf = _com_util::ConvertBSTRToString((_bstr_t)v1);
三、字符串轉(zhuǎn)換為其它數(shù)據(jù)類型
strcpy(temp,"123");
短整型(int)
i = atoi(temp);
長整型(long)
l = atol(temp);
浮點(diǎn)(double)
d = atof(temp);
四、其它數(shù)據(jù)類型轉(zhuǎn)換到CString
使用CString的成員函數(shù)Format來轉(zhuǎn)換,例如:
整數(shù)(int)
str.Format("%d",i);
浮點(diǎn)數(shù)(float)
str.Format("%f",i);
字符串指針(char *)等已經(jīng)被CString構(gòu)造函數(shù)支持的數(shù)據(jù)類型可以直接賦值
str = username;
五、BSTR、_bstr_t與CComBSTR
CComBSTR、_bstr_t是對BSTR的封裝,BSTR是指向字符串的32位指針。
char *轉(zhuǎn)換到BSTR可以這樣: BSTR b=_com_util::ConvertStringToBSTR("數(shù)據(jù)");///使用前需要加上頭文件comutil.h
反之可以使用char *p=_com_util::ConvertBSTRToString(b);
六、VARIANT 、_variant_t 與 COleVariant
VARIANT的結(jié)構(gòu)可以參考頭文件VC98\Include\OAIDL.H中關(guān)于結(jié)構(gòu)體tagVARIANT的定義。
對于VARIANT變量的賦值：首先給vt成員賦值，指明數(shù)據(jù)類型，再對聯(lián)合結(jié)構(gòu)中相同數(shù)據(jù)類型的變量賦值，舉個例子：
VARIANT va;
int a=2001;
va.vt=VT_I4;///指明整型數(shù)據(jù)
va.lVal=a; ///賦值
對于不馬上賦值的VARIANT，最好先用Void VariantInit(VARIANTARG FAR* pvarg);進(jìn)行初始化,其本質(zhì)是將vt設(shè)置為VT_EMPTY,下表我們列舉vt與常用數(shù)據(jù)的對應(yīng)關(guān)系:
unsigned char bVal; VT_UI1
short iVal; VT_I2
long lVal; VT_I4
float fltVal; VT_R4
double dblVal; VT_R8
VARIANT_BOOL boolVal; VT_BOOL
SCODE scode; VT_ERROR
CY cyVal; VT_CY
DATE date; VT_DATE
BSTR bstrVal; VT_BSTR
IUnknown FAR* punkVal; VT_UNKNOWN
IDispatch FAR* pdispVal; VT_DISPATCH
SAFEARRAY FAR* parray; VT_ARRAY|*
unsigned char FAR* pbVal; VT_BYREF|VT_UI1
short FAR* piVal; VT_BYREF|VT_I2
long FAR* plVal; VT_BYREF|VT_I4
float FAR* pfltVal; VT_BYREF|VT_R4
double FAR* pdblVal; VT_BYREF|VT_R8
VARIANT_BOOL FAR* pboolVal; VT_BYREF|VT_BOOL
SCODE FAR* pscode; VT_BYREF|VT_ERROR
CY FAR* pcyVal; VT_BYREF|VT_CY
DATE FAR* pdate; VT_BYREF|VT_DATE
BSTR FAR* pbstrVal; VT_BYREF|VT_BSTR
IUnknown FAR* FAR* ppunkVal; VT_BYREF|VT_UNKNOWN
IDispatch FAR* FAR* ppdispVal; VT_BYREF|VT_DISPATCH
SAFEARRAY FAR* FAR* pparray; VT_ARRAY|*
VARIANT FAR* pvarVal; VT_BYREF|VT_VARIANT
void FAR* byref; VT_BYREF
_variant_t是VARIANT的封裝類，其賦值可以使用強(qiáng)制類型轉(zhuǎn)換，其構(gòu)造函數(shù)會自動處理這些數(shù)據(jù)類型。
例如：
long l=222;
ing i=100;
_variant_t lVal(l);
lVal = (long)i;
COleVariant的使用與_variant_t的方法基本一樣，請參考如下例子：
COleVariant v3 = "字符串", v4 = (long)1999;
CString str =(BSTR)v3.pbstrVal;
long i = v4.lVal;
七、其它
對消息的處理中我們經(jīng)常需要將WPARAM或LPARAM等32位數(shù)據(jù)(DWORD)分解成兩個16位數(shù)據(jù)(WORD),例如：
LPARAM lParam;
WORD lovalue = LOWORD(lParam);///取低16位
WORD hivalue = HIWORD(lParam);///取高16位
對于16位的數(shù)據(jù)(WORD)我們可以用同樣的方法分解成高低兩個8位數(shù)據(jù)(BYTE),例如:
WORD wvalue;
BYTE lovalue = LOBYTE(wvalue);///取低8位
BYTE hivalue = HIBYTE(wvalue);///取高8位
CString csStr;
BSTR a = csStr.AllocSysString();
CString str;
Holder = theApp.m_pADOSet->GetCollect("typeid");
str = Holder.vt==VT_NULL?"":(char*)(_bstr_t)Holder;//字符串
Holder = theApp.m_pADOSet->GetCollect("price");
str.Format("%.2f", Holder.vt==VT_NULL?0:Holder.dblVal);//實(shí)數(shù)型
Holder = theApp.m_pADOSet->GetCollect("Date");//日期類型
CTime time;
time = Holder;
time.Format("%Y-%M-%d")
所有的variant類型都可以直接轉(zhuǎn)化為字符串指針
如：str=(_BSTR_T)var;
