/*
將 _variant_t 類型的變量，轉(zhuǎn)換成字符串（比如如果是數(shù)字，則轉(zhuǎn)換成數(shù)字對(duì)應(yīng)的字符串 ：如 10.2 -> "10.200000"）

*/

_variant_t var; 

CString str; //轉(zhuǎn)換以后的字符串



//以下代碼演示如何轉(zhuǎn)換為C標(biāo)準(zhǔn)字符串型
if (var.vt == VT_I4)
{
    long lNum;
    char szCh[21];
    str=var.bstrVal;
    WideCharToMultiByte
             (CP_ACP, 0, var.bstrVal, -1,
              szCh, sizeof(szCh), NULL, NULL);
}

//以下代碼演示如何轉(zhuǎn)換成邏輯型
if( var.vt == VT_BOOL)
{
    BOOL bVar;
    lNum=var.lVal;
    bVar= var.boolVar==0? FALSE : TRUE;
}

//以下代碼演示為其余類型（補(bǔ)充）
switch(var.vt)
{

case VT_BSTR:         //var is BSTR type
     str=var.bstrVal;
     break;

case VT_I2:           //var is short int type
     str.Format("%d",(int)var.iVal);
     break;

case VT_I4:          //var is long int type
     str.Format("%d",var.lVal);
     break;

case VT_R4:         //var is float type
     str.Format("%10.6f",(double)var.fltVal);
     break;

case VT_R8:         //var is double type
     str.Format("%10.6f",var.dblVal);
     break;

case VT_CY:        //var is CY type
     str=COleCurrency(var).Format();
     break;

case VT_DATE:     //var is DATE type
     str=COleDateTime(var).Format();
     break;

case VT_BOOL:     //var is  VARIANT_BOOL
     str= (var.boolVal==0) ?"FALSE": "TRUE";
     break;

default:
     str.Format("Unk type %d\n",var.vt);
     TRACE("Unknown type %d\n",var.vt);
}