C++读取注册表的实现方法

#ifndef __GETREGVALUE_H__
#define __GETREGVALUE_H__

#include <string>

//---------------------------------------------------------------
//function: 
//     GetRegValue 获取注册表中指定键的值
//Access:
//      public 
//Parameter:
//     [in] int nKeyType - 注册表项的类型，传入的参数只可能是以下数值：
//               0:HKEY_CLASSES_ROOT
//               1:HKEY_CURRENT_USER
//               2:HKEY_LOCAL_MACHINE
//               3:HKEY_USERS
//               4:HKEY_PERFORMANCE_DATA
//               5:HKEY_CURRENT_CONFIG
//               6:HKEY_DYN_DATA
//               7:HKEY_CURRENT_USER_LOCAL_SETTINGS
//               8:HKEY_PERFORMANCE_TEXT
//               9:HKEY_PERFORMANCE_NLSTEXT
//     [in] const std::string & strUrl - 要查找 的键的路径
//     [in] const std::string & strKey - 指定的键
//Returns:
//     std::string - 指定键的值
//Remarks:
//     ...
//author:  luoweifu
//---------------------------------------------------------------
std::string GetRegValue(int nKeyType,const std::string& strUrl,const std::string& strKey);

//可移植版本 wstring => string
std::string ws2s(const std::wstring& ws);

//可移植版本 string => wstring
std::wstring s2ws(const std::string& s);


#endif //__GETREGVALUE_H__

#include "stdafx.h"
#include <Windows.h>
#include "GetRegValue.h"

//可移植版本 wstring => string
std::string ws2s(const std::wstring& ws)
{
  std::string curLocale = setlocale(LC_ALL,"");
  const wchar_t* _Source = ws.c_str();
  size_t _Dsize = wcstombs(NULL,_Source,0) + 1;
  char *_Dest = new char[_Dsize];
  memset(_Dest,_Dsize);
  wcstombs(_Dest,_Dsize);
  std::string result = _Dest;
  delete []_Dest;
  setlocale(LC_ALL,curLocale.c_str());
  return result;
}

//可移植版本 string => wstring
std::wstring s2ws(const std::string& s)
{
  std::string curLocale = setlocale(LC_ALL,""); 
  const char* _Source = s.c_str();
  size_t _Dsize = mbstowcs(NULL,0) + 1;
  wchar_t *_Dest = new wchar_t[_Dsize];
  wmemset(_Dest,_Dsize);
  mbstowcs(_Dest,_Dsize);
  std::wstring result = _Dest;
  delete []_Dest;
  setlocale(LC_ALL,curLocale.c_str());
  return result;
}

std::string GetRegValue(int nKeyType,const std::string& strKey)
{
  std::string strValue("");
  HKEY hKey = NULL;
  HKEY hKeyResult = NULL;
  DWORD dwSize   = 0;
  DWORD dwDataType = 0;
  std::wstring wstrUrl = s2ws(strUrl);
  std::wstring wstrKey = s2ws(strKey);

  switch(nKeyType)
  {
  case 0:
    {
      hKey = HKEY_CLASSES_ROOT;
      break;
    }
  case 1:
    {
      hKey = HKEY_CURRENT_USER;
      break;
    }
  case 2:
    {
      hKey = HKEY_LOCAL_MACHINE;
      break;
    }
  case 3:
    {
      hKey = HKEY_USERS;
      break;
    }
  case 4:
    {
      hKey = HKEY_PERFORMANCE_DATA;
      break;
    }
  case 5:
    {
      hKey = HKEY_CURRENT_CONFIG;
      break;
    }
  case 6:
    {
      hKey = HKEY_DYN_DATA;
      break;
    }
  case 7:
    {
      hKey = HKEY_CURRENT_USER_LOCAL_SETTINGS;
      break;
    }
  case 8:
    {
      hKey = HKEY_PERFORMANCE_TEXT;
      break;
    }
  case 9:
    {
      hKey = HKEY_PERFORMANCE_NLSTEXT;
      break;
    }
  default:
    {
      return strValue;
    }
  }

  //打开注册表
  if(ERROR_SUCCESS == ::RegOpenKeyEx(hKey,wstrUrl.c_str(),KEY_QUERY_VALUE,&hKeyResult))
  {
    // 获取缓存的长度dwSize及类型dwDataType
    ::RegQueryValueEx(hKeyResult,wstrKey.c_str(),&dwDataType,NULL,&dwSize); 
    switch (dwDataType)
    {
    case REG_MULTI_SZ:
      {
        //分配内存大小
        BYTE* lpValue = new BYTE[dwSize];
        //获取注册表中指定的键所对应的值
        LONG lRet = ::RegQueryValueEx(hKeyResult,lpValue,&dwSize);
        delete[] lpValue;
        break;
      }
    case REG_SZ:
      {
        //分配内存大小
        wchar_t* lpValue = new wchar_t[dwSize];
        memset(lpValue,dwSize * sizeof(wchar_t));
        //获取注册表中指定的键所对应的值
        if (ERROR_SUCCESS == ::RegQueryValueEx(hKeyResult,(LPBYTE)lpValue,&dwSize))
        {
          std::wstring wstrValue(lpValue);
          strValue = ws2s(wstrValue);
        }
        delete[] lpValue;
        break;
      }
    default:
      break;
    }
  }

  //关闭注册表
  ::RegCloseKey(hKeyResult);


  return strValue;
}

#include "stdafx.h"
#include <string>
#include "GetRegValue.h"

int _tmain(int argc,_TCHAR* argv[])
{
  std::string strValue = GetRegValue(2,"SOFTWARE360SafeLiveup","mid");
  return 0;
}