ADO中_variant_t变量的使用与转换

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用ADO做数据库，有个麻烦的事情就是_variant_t变量的使用，使用本例中封装的CConvert类转换就方便了。

 

// Convert.h: interface for the CConvert class.
//
//////////////////////////////////////////////////////////////////////
#if !defined(AFX_CONVERT_H__EC38F865_4607_4659_BAC8_AA6096C50EC7__INCLUDED_)
#define AFX_CONVERT_H__EC38F865_4607_4659_BAC8_AA6096C50EC7__INCLUDED_
#if _MSC_VER > 1000
#pragma once
#endif // _MSC_VER > 1000
//////////////////////////////////////////////////////////////////////
// Construction/Destruction
/*
* Copyright (c) 2010,[email protected]
* All rights reserved.
*
* 文件名称：Convert.h
* 文件标识：数据类型转换
* 摘    要：主要简化ADO中数据类型的转换
*
* 当前版本：1.0
* 作    者：[email protected]
* 完成日期：2010年5月11日
* 发布Blog：http://blog.csdn.net/zyq5945/
*
*/
//////////////////////////////////////////////////////////////////////
#define TS(value) CConvert::ToString(value)
class CConvert
{

public:
    static CString ToString(BYTE btValue);
    static CString ToString(int iValue);
    static CString ToString(unsigned int iValue);
    static CString ToString(long lValue);
    static CString ToString(unsigned long lValue);
    static CString ToString(__int64 i64Value);
    static CString ToString(unsigned __int64 i64Value);
    static CString ToString(float fltValue);
    static CString ToString(double dblValue);
    static CString ToString(const COleDateTime& time);
    static CString ToString(const _variant_t& var);
public:
    static BYTE ToByte(LPCTSTR lpszValue);
    static int ToInt(LPCTSTR lpszValue);
    static unsigned int ToUInt(LPCTSTR lpszValue);
    static long ToLong(LPCTSTR lpszValue);
    static unsigned long ToULong(LPCTSTR lpszValue);
    static __int64 ToInt64(LPCTSTR lpszValue);
    static unsigned __int64 ToUInt64(LPCTSTR lpszValue);
    static float ToFloat(LPCTSTR lpszValue);
    static double ToDouble(LPCTSTR lpszValue);
    static COleDateTime ToTime(LPCTSTR lpszValue);
    static _variant_t ToVariant(const COleDateTime& time);
};
extern CConvert Convert;
#endif // !defined(AFX_CONVERT_H__EC38F865_4607_4659_BAC8_AA6096C50EC7__INCLUDED_)

// Convert.h: interface for the CConvert class. // ////////////////////////////////////////////////////////////////////// #if !defined(AFX_CONVERT_H__EC38F865_4607_4659_BAC8_AA6096C50EC7__INCLUDED_) #define AFX_CONVERT_H__EC38F865_4607_4659_BAC8_AA6096C50EC7__INCLUDED_ #if _MSC_VER > 1000 #pragma once #endif // _MSC_VER > 1000 ////////////////////////////////////////////////////////////////////// // Construction/Destruction /* * Copyright (c) 2010,[email protected] * All rights reserved. * * 文件名称：Convert.h * 文件标识：数据类型转换 * 摘 要：主要简化ADO中数据类型的转换 * * 当前版本：1.0 * 作 者：[email protected] * 完成日期：2010年5月11日 * 发布Blog：http://blog.csdn.net/zyq5945/ * */ ////////////////////////////////////////////////////////////////////// #define TS(value) CConvert::ToString(value) class CConvert { public: static CString ToString(BYTE btValue); static CString ToString(int iValue); static CString ToString(unsigned int iValue); static CString ToString(long lValue); static CString ToString(unsigned long lValue); static CString ToString(__int64 i64Value); static CString ToString(unsigned __int64 i64Value); static CString ToString(float fltValue); static CString ToString(double dblValue); static CString ToString(const COleDateTime& time); static CString ToString(const _variant_t& var); public: static BYTE ToByte(LPCTSTR lpszValue); static int ToInt(LPCTSTR lpszValue); static unsigned int ToUInt(LPCTSTR lpszValue); static long ToLong(LPCTSTR lpszValue); static unsigned long ToULong(LPCTSTR lpszValue); static __int64 ToInt64(LPCTSTR lpszValue); static unsigned __int64 ToUInt64(LPCTSTR lpszValue); static float ToFloat(LPCTSTR lpszValue); static double ToDouble(LPCTSTR lpszValue); static COleDateTime ToTime(LPCTSTR lpszValue); static _variant_t ToVariant(const COleDateTime& time); }; extern CConvert Convert; #endif // !defined(AFX_CONVERT_H__EC38F865_4607_4659_BAC8_AA6096C50EC7__INCLUDED_)

 

 

// Convert.cpp: implementation of the CConvert class.
//
//////////////////////////////////////////////////////////////////////
#include "stdafx.h"
#include "Convert.h"
#include <comutil.h>
#include <comdef.h>
#ifdef _DEBUG
#undef THIS_FILE
static char THIS_FILE[]=__FILE__;
#define new DEBUG_NEW
#endif
//////////////////////////////////////////////////////////////////////
// Construction/Destruction
/*
* Copyright (c) 2010,[email protected]
* All rights reserved.
*
* 文件名称：Convert.cpp
* 文件标识：数据类型转换
* 摘    要：主要简化ADO中数据类型的转换
*
* 当前版本：1.0
* 作    者：zyq5945
* 完成日期：2010年5月11日
* 发布Blog：http://blog.csdn.net/zyq5945/
*
*/
//////////////////////////////////////////////////////////////////////
CConvert Convert;
CString CConvert::ToString(BYTE btValue)
{
    CString strValue;
    strValue.Format(_T("%d"), btValue);
    return strValue;
}
CString CConvert::ToString(int iValue)
{
    CString strValue;
    strValue.Format(_T("%d"), iValue);
    return strValue;
}
CString CConvert::ToString(unsigned int iValue)
{
    CString strValue;
    strValue.Format(_T("%u"), iValue);
    return strValue;
}
CString CConvert::ToString(long lValue)
{
    CString strValue;
    strValue.Format(_T("%d"), lValue);
    return strValue;
}
CString CConvert::ToString(unsigned long lValue)
{
    CString strValue;
    strValue.Format(_T("%u"), lValue);
    return strValue;
}
CString CConvert::ToString(__int64 i64Value)
{
    CString strValue;
    strValue.Format(_T("%I64d"), i64Value);
    return strValue;
}
CString CConvert::ToString(unsigned __int64 i64Value)
{
    CString strValue;
    strValue.Format(_T("%I64u"), i64Value);
    return strValue;
}
CString CConvert::ToString(float fltValue)
{
    CString strValue;
    strValue.Format(_T("%f"), fltValue);
    return strValue;
}
CString CConvert::ToString(double dblValue)
{
    CString strValue;
    strValue.Format(_T("%f"), dblValue);
    return strValue;
}
// 时间输出格式：2010-05-06 22:07:08
CString CConvert::ToString(const COleDateTime& time)
{
    CString strValue;
    strValue = time.Format(_T("%Y-%m-%d %H:%M:%S"));
    return strValue;
}
CString CConvert::ToString(const _variant_t& var)
{
    CString strValue;
    switch (var.vt)
    {
    case VT_BSTR: //字符串
    case VT_LPSTR:
    case VT_LPWSTR:
        strValue = (LPCTSTR)(_bstr_t)var;
        break;
    case VT_I1:   //无符号字符
    case VT_UI1:
        strValue.Format(_T("%d"), var.bVal);
        break;
    case VT_I2:   //短整型
        strValue.Format(_T("%d"), var.iVal);
        break;
    case VT_UI2:   //无符号短整型
        strValue.Format(_T("%u"), var.uiVal);
        break;
    case VT_INT: //整型
        strValue.Format(_T("%d"), var.intVal);
        break;
    case VT_I4:   //整型
    case VT_I8:   //长整型
        strValue.Format(_T("%d"), var.lVal);
        break;
    case VT_UINT:   //无符号整型
        strValue.Format(_T("%d"), var.uintVal);
        break;
    case VT_UI4:    //无符号整型
    case VT_UI8:    //无符号长整型
        strValue.Format(_T("%d"), var.ulVal);
        break;
    case VT_VOID:
        strValue.Format(_T("%08x"), var.byref);
        break;
    case VT_R4:   //浮点型
        strValue.Format(_T("%f"), var.fltVal);
        break;
    case VT_R8:   //双精度型
        strValue.Format(_T("%f"), var.dblVal);
        break;
    case VT_DECIMAL: //小数
        strValue.Format(_T("%f"), (double)var);
        break;
    case VT_CY:
        {
            COleCurrency cy = var.cyVal;
            strValue = cy.Format();
        }
        break;
    case VT_BLOB:
    case VT_BLOB_OBJECT:
    case 0x2011:
        strValue = _T("[BLOB]");
        break;
    case VT_BOOL:   //布尔型
        strValue = var.boolVal ? _T("TRUE") : _T("FALSE");
        break;
    case VT_DATE: //日期型
        {
            DATE dt = var.date;
            COleDateTime da = COleDateTime(dt);
            strValue = da.Format(_T("%Y-%m-%d %H:%M:%S"));
        }
        break;
    case VT_NULL://NULL值
    case VT_EMPTY:   //空
        strValue = _T("");
        break;
    case VT_UNKNOWN:   //未知类型
    default:
        strValue = _T("VT_UNKNOW");
        break;
    }

    return strValue;
}
BYTE CConvert::ToByte(LPCTSTR lpszValue)
{
    BYTE btValue;
    btValue = (BYTE)_ttoi(lpszValue);
    return btValue;
}
int CConvert::ToInt(LPCTSTR lpszValue)
{
    int iValue;
    iValue = _ttoi(lpszValue);
    return iValue;
}
unsigned int CConvert::ToUInt(LPCTSTR lpszValue)
{
    unsigned int iValue;
    iValue = _ttoi(lpszValue);
    return iValue;
}
long CConvert::ToLong(LPCTSTR lpszValue)
{
    long lValue;
    lValue = _ttol(lpszValue);
    return lValue;
}
unsigned long CConvert::ToULong(LPCTSTR lpszValue)
{
    unsigned long lValue;
    lValue = _ttol(lpszValue);
    return lValue;
}
__int64 CConvert::ToInt64(LPCTSTR lpszValue)
{
    __int64 i64Value;
    i64Value = _ttoi64(lpszValue);
    return i64Value;
}
unsigned __int64 CConvert::ToUInt64(LPCTSTR lpszValue)
{
    unsigned __int64 i64Value;
    i64Value = _ttoi64(lpszValue);
    return i64Value;
}
float CConvert::ToFloat(LPCTSTR lpszValue)
{
    float fltValue;
#ifdef _MBCS
    fltValue = (float)atof(lpszValue);
#else
    fltValue = (float)wtof(lpszValue);
#endif
    return fltValue;
}
double CConvert::ToDouble(LPCTSTR lpszValue)
{
    double dblValue;
#ifdef _MBCS
    dblValue = atof(lpszValue);
#else
    dblValue = wtof(lpszValue);
#endif
    return dblValue;
}
// 时间格式例子：2010-05-06 22:07:08
//               2010 05 06 22 07 08
//               2010:05:06 22:07:08
//               2010-05-06-22-07-08
// 只要是“- :”分割的时间格式都符合
COleDateTime CConvert::ToTime(LPCTSTR lpszValue)
{
    unsigned int iArray[6] = {2010, 5, 11, 12, 00, 00};
    int nIndex = 0;
#if _MSC_VER >= 1310  //VC6.0不支持CStringAlt::Tokenize
    CString strTmp;
    int curPos = 0;
    CString strValue(lpszValue);

    strTmp = strValue.Tokenize(_T("- :"),curPos);
    while (strTmp != _T("") && nIndex <6)
    {
        iArray[nIndex++] = ToUInt(strTmp);
        strTmp = strValue.Tokenize(_T("- :"), curPos);
    };
#else
    TCHAR tChar[MAX_PATH] = {0};
    TCHAR tCharTmp[MAX_PATH] = {0};
    TCHAR seps[]   = "- :";
    TCHAR *next_token = NULL;
    ASSERT(_tcslen(lpszValue) < MAX_PATH);
    RtlCopyMemory(tChar, lpszValue, _tcslen(lpszValue) * sizeof(TCHAR));
    next_token = _tcstok(tChar, seps);
    while ( next_token != NULL && nIndex <6)
    {
        iArray[nIndex++] = _ttoi(next_token);
        next_token = _tcstok( NULL, seps);
    }

#endif
    COleDateTime time(iArray[0], iArray[1], iArray[2],
        iArray[3], iArray[4], iArray[5]);
    return time;
}
_variant_t CConvert::ToVariant(const COleDateTime& time)
{
    _variant_t vtVal;

    vtVal.vt = VT_DATE;
    vtVal.date = time;
    return vtVal;
}

// Convert.cpp: implementation of the CConvert class. // ////////////////////////////////////////////////////////////////////// #include "stdafx.h" #include "Convert.h" #include <comutil.h> #include <comdef.h> #ifdef _DEBUG #undef THIS_FILE static char THIS_FILE[]=__FILE__; #define new DEBUG_NEW #endif ////////////////////////////////////////////////////////////////////// // Construction/Destruction /* * Copyright (c) 2010,[email protected] * All rights reserved. * * 文件名称：Convert.cpp * 文件标识：数据类型转换 * 摘 要：主要简化ADO中数据类型的转换 * * 当前版本：1.0 * 作 者：zyq5945 * 完成日期：2010年5月11日 * 发布Blog：http://blog.csdn.net/zyq5945/ * */ ////////////////////////////////////////////////////////////////////// CConvert Convert; CString CConvert::ToString(BYTE btValue) { CString strValue; strValue.Format(_T("%d"), btValue); return strValue; } CString CConvert::ToString(int iValue) { CString strValue; strValue.Format(_T("%d"), iValue); return strValue; } CString CConvert::ToString(unsigned int iValue) { CString strValue; strValue.Format(_T("%u"), iValue); return strValue; } CString CConvert::ToString(long lValue) { CString strValue; strValue.Format(_T("%d"), lValue); return strValue; } CString CConvert::ToString(unsigned long lValue) { CString strValue; strValue.Format(_T("%u"), lValue); return strValue; } CString CConvert::ToString(__int64 i64Value) { CString strValue; strValue.Format(_T("%I64d"), i64Value); return strValue; } CString CConvert::ToString(unsigned __int64 i64Value) { CString strValue; strValue.Format(_T("%I64u"), i64Value); return strValue; } CString CConvert::ToString(float fltValue) { CString strValue; strValue.Format(_T("%f"), fltValue); return strValue; } CString CConvert::ToString(double dblValue) { CString strValue; strValue.Format(_T("%f"), dblValue); return strValue; } // 时间输出格式：2010-05-06 22:07:08 CString CConvert::ToString(const COleDateTime& time) { CString strValue; strValue = time.Format(_T("%Y-%m-%d %H:%M:%S")); return strValue; } CString CConvert::ToString(const _variant_t& var) { CString strValue; switch (var.vt) { case VT_BSTR: //字符串 case VT_LPSTR: case VT_LPWSTR: strValue = (LPCTSTR)(_bstr_t)var; break; case VT_I1: //无符号字符 case VT_UI1: strValue.Format(_T("%d"), var.bVal); break; case VT_I2: //短整型 strValue.Format(_T("%d"), var.iVal); break; case VT_UI2: //无符号短整型 strValue.Format(_T("%u"), var.uiVal); break; case VT_INT: //整型 strValue.Format(_T("%d"), var.intVal); break; case VT_I4: //整型 case VT_I8: //长整型 strValue.Format(_T("%d"), var.lVal); break; case VT_UINT: //无符号整型 strValue.Format(_T("%d"), var.uintVal); break; case VT_UI4: //无符号整型 case VT_UI8: //无符号长整型 strValue.Format(_T("%d"), var.ulVal); break; case VT_VOID: strValue.Format(_T("%08x"), var.byref); break; case VT_R4: //浮点型 strValue.Format(_T("%f"), var.fltVal); break; case VT_R8: //双精度型 strValue.Format(_T("%f"), var.dblVal); break; case VT_DECIMAL: //小数 strValue.Format(_T("%f"), (double)var); break; case VT_CY: { COleCurrency cy = var.cyVal; strValue = cy.Format(); } break; case VT_BLOB: case VT_BLOB_OBJECT: case 0x2011: strValue = _T("[BLOB]"); break; case VT_BOOL: //布尔型 strValue = var.boolVal ? _T("TRUE") : _T("FALSE"); break; case VT_DATE: //日期型 { DATE dt = var.date; COleDateTime da = COleDateTime(dt); strValue = da.Format(_T("%Y-%m-%d %H:%M:%S")); } break; case VT_NULL://NULL值 case VT_EMPTY: //空 strValue = _T(""); break; case VT_UNKNOWN: //未知类型 default: strValue = _T("VT_UNKNOW"); break; } return strValue; } BYTE CConvert::ToByte(LPCTSTR lpszValue) { BYTE btValue; btValue = (BYTE)_ttoi(lpszValue); return btValue; } int CConvert::ToInt(LPCTSTR lpszValue) { int iValue; iValue = _ttoi(lpszValue); return iValue; } unsigned int CConvert::ToUInt(LPCTSTR lpszValue) { unsigned int iValue; iValue = _ttoi(lpszValue); return iValue; } long CConvert::ToLong(LPCTSTR lpszValue) { long lValue; lValue = _ttol(lpszValue); return lValue; } unsigned long CConvert::ToULong(LPCTSTR lpszValue) { unsigned long lValue; lValue = _ttol(lpszValue); return lValue; } __int64 CConvert::ToInt64(LPCTSTR lpszValue) { __int64 i64Value; i64Value = _ttoi64(lpszValue); return i64Value; } unsigned __int64 CConvert::ToUInt64(LPCTSTR lpszValue) { unsigned __int64 i64Value; i64Value = _ttoi64(lpszValue); return i64Value; } float CConvert::ToFloat(LPCTSTR lpszValue) { float fltValue; #ifdef _MBCS fltValue = (float)atof(lpszValue); #else fltValue = (float)wtof(lpszValue); #endif return fltValue; } double CConvert::ToDouble(LPCTSTR lpszValue) { double dblValue; #ifdef _MBCS dblValue = atof(lpszValue); #else dblValue = wtof(lpszValue); #endif return dblValue; } // 时间格式例子：2010-05-06 22:07:08 // 2010 05 06 22 07 08 // 2010:05:06 22:07:08 // 2010-05-06-22-07-08 // 只要是“- :”分割的时间格式都符合 COleDateTime CConvert::ToTime(LPCTSTR lpszValue) { unsigned int iArray[6] = {2010, 5, 11, 12, 00, 00}; int nIndex = 0; #if _MSC_VER >= 1310 //VC6.0不支持CStringAlt::Tokenize CString strTmp; int curPos = 0; CString strValue(lpszValue); strTmp = strValue.Tokenize(_T("- :"),curPos); while (strTmp != _T("") && nIndex <6) { iArray[nIndex++] = ToUInt(strTmp); strTmp = strValue.Tokenize(_T("- :"), curPos); }; #else TCHAR tChar[MAX_PATH] = {0}; TCHAR tCharTmp[MAX_PATH] = {0}; TCHAR seps[] = "- :"; TCHAR *next_token = NULL; ASSERT(_tcslen(lpszValue) < MAX_PATH); RtlCopyMemory(tChar, lpszValue, _tcslen(lpszValue) * sizeof(TCHAR)); next_token = _tcstok(tChar, seps); while ( next_token != NULL && nIndex <6) { iArray[nIndex++] = _ttoi(next_token); next_token = _tcstok( NULL, seps); } #endif COleDateTime time(iArray[0], iArray[1], iArray[2], iArray[3], iArray[4], iArray[5]); return time; } _variant_t CConvert::ToVariant(const COleDateTime& time) { _variant_t vtVal; vtVal.vt = VT_DATE; vtVal.date = time; return vtVal; }

 

由于_variant_t重载了以下等号运算符，所以下面类型可以直接给_variant_t赋值

 

VARIANT

VARIANT*

_variant_t

short

long

float

double

CY

_bstr_t

wchar_t

char

IDispatch*

bool

IUnknown*

DECIMAL

BYTE

char

unsigned short

unsigned long

int

unsigned int

__int64

unsigned __int64

VARIANT VARIANT* _variant_t short long float double CY _bstr_t wchar_t char IDispatch* bool IUnknown* DECIMAL BYTE char unsigned short unsigned long int unsigned int __int64 unsigned __int64

 

由于COleDateTime 重载了以下等号运算符，所以下面类型可以直接给COleDateTime 赋值

 

VARIANT

DATE

time_t

__time64_t

SYSTEMTIME

FILETIME

UDATE

VARIANT DATE time_t __time64_t SYSTEMTIME FILETIME UDATE

 

本例中CConvert类也增加了一个ToVariant函数把COleDateTime转换为_variant_t类型变量

_variant_t varValue;
CString strValue;
COleDateTime dt;
try
{
    // 写入各字段值
    m_pRecordset->AddNew();
    // byte变量
    GetDlgItemText(IDC_EDIT1, strValue);
    varValue = CConvert::ToByte(strValue);
    m_pRecordset->PutCollect("tByte", varValue);

    // int变量
    GetDlgItemText(IDC_EDIT2, strValue);
    varValue = (long)CConvert::ToInt(strValue);
    m_pRecordset->PutCollect("tInt", varValue);
    // long变量
    GetDlgItemText(IDC_EDIT3, strValue);
    varValue = CConvert::ToLong(strValue);
    m_pRecordset->PutCollect("tLong", varValue);
    // float变量
    GetDlgItemText(IDC_EDIT4, strValue);
    varValue = CConvert::ToFloat(strValue);
    m_pRecordset->PutCollect("tFloat", varValue);
    // double变量
    GetDlgItemText(IDC_EDIT5, strValue);
    varValue = CConvert::ToDouble(strValue);
    m_pRecordset->PutCollect("tDouble", varValue);
    // COleDateTime变量
    GetDlgItemText(IDC_EDIT6, strValue);
    dt = CConvert::ToTime(strValue);
    varValue = CConvert::ToVariant(dt);
    m_pRecordset->PutCollect("tTime", varValue);
    // bool变量
    GetDlgItemText(IDC_EDIT7, strValue);
    if (!strValue.CompareNoCase("TRUE"))
    {
        varValue = true;
    }
    else
    {
        varValue = false;
    }
    m_pRecordset->PutCollect("tBool", varValue);
    // 字符串变量
    GetDlgItemText(IDC_EDIT8, strValue);
    varValue = strValue;
    m_pRecordset->PutCollect("tText", varValue);
    m_pRecordset->Update();

    // 更新显示其库内容
    int nCurSel = m_list.GetItemCount();
    ADOListRecord();
    SetListSel(nCurSel);

    AfxMessageBox("插入成功!");
}
catch(_com_error& e)
{
    dump_com_error(e);
}

_variant_t varValue; CString strValue; COleDateTime dt; try { // 写入各字段值 m_pRecordset->AddNew(); // byte变量 GetDlgItemText(IDC_EDIT1, strValue); varValue = CConvert::ToByte(strValue); m_pRecordset->PutCollect("tByte", varValue); // int变量 GetDlgItemText(IDC_EDIT2, strValue); varValue = (long)CConvert::ToInt(strValue); m_pRecordset->PutCollect("tInt", varValue); // long变量 GetDlgItemText(IDC_EDIT3, strValue); varValue = CConvert::ToLong(strValue); m_pRecordset->PutCollect("tLong", varValue); // float变量 GetDlgItemText(IDC_EDIT4, strValue); varValue = CConvert::ToFloat(strValue); m_pRecordset->PutCollect("tFloat", varValue); // double变量 GetDlgItemText(IDC_EDIT5, strValue); varValue = CConvert::ToDouble(strValue); m_pRecordset->PutCollect("tDouble", varValue); // COleDateTime变量 GetDlgItemText(IDC_EDIT6, strValue); dt = CConvert::ToTime(strValue); varValue = CConvert::ToVariant(dt); m_pRecordset->PutCollect("tTime", varValue); // bool变量 GetDlgItemText(IDC_EDIT7, strValue); if (!strValue.CompareNoCase("TRUE")) { varValue = true; } else { varValue = false; } m_pRecordset->PutCollect("tBool", varValue); // 字符串变量 GetDlgItemText(IDC_EDIT8, strValue); varValue = strValue; m_pRecordset->PutCollect("tText", varValue); m_pRecordset->Update(); // 更新显示其库内容 int nCurSel = m_list.GetItemCount(); ADOListRecord(); SetListSel(nCurSel); AfxMessageBox("插入成功!"); } catch(_com_error& e) { dump_com_error(e); }

 

参考文献：ADO数据库编程-总结2