在VC++中通過sqlite3.dll接口對sqlite數據庫進行操作，包括打開數據庫，插入，查詢數據庫等，如果操作接口輸入參數包含中文字符，會導致操作異常。例如調用sqlite3_open打開數據庫文件，如果文件路徑出現中文，就會導致打開失敗。sqlite3_exec執行sql語句，如果包含中文對應字符就會變成亂碼。
這是由于sqlite數據庫使用的是UTF-8編碼方式，而傳入的字符串是ASCII編碼或Unicode編碼，導致字符串格式錯誤。解決方案是在調用sqlite接口之前，先將字符串轉換成UTF-8編碼，以下提供各種字符串編碼轉換函數。
//UTF-8轉Unicode
std::wstring Utf82Unicode(const std::string& utf8string)
{
int widesize = ::MultiByteToWideChar(CP_UTF8, 0, utf8string.c_str(), -1, NULL, 0);
if (widesize == ERROR_NO_UNICODE_TRANSLATION)
{
throw std::exception("Invalid UTF-8 sequence.");
}
if (widesize == 0)
{
throw std::exception("Error in conversion.");
}
std::vector<wchar_t> resultstring(widesize);
int convresult = ::MultiByteToWideChar(CP_UTF8, 0, utf8string.c_str(), -1, &resultstring[0], widesize);
if (convresult != widesize)
{
throw std::exception("La falla!");
}
return std::wstring(&resultstring[0]);
}
//unicode 轉為 ascii
string WideByte2Acsi(wstring& wstrcode)
{
int asciisize = ::WideCharToMultiByte(CP_OEMCP, 0, wstrcode.c_str(), -1, NULL, 0, NULL, NULL);
if (asciisize == ERROR_NO_UNICODE_TRANSLATION)
{
throw std::exception("Invalid UTF-8 sequence.");
}
if (asciisize == 0)
{
throw std::exception("Error in conversion.");
}
std::vector<char> resultstring(asciisize);
int convresult =::WideCharToMultiByte(CP_OEMCP, 0, wstrcode.c_str(), -1, &resultstring[0], asciisize, NULL, NULL);
if (convresult != asciisize)
{
throw std::exception("La falla!");
}
return std::string(&resultstring[0]);
}
//utf-8 轉 ascii
string UTF_82ASCII(string& strUtf8Code)
{
string strRet("");
//先把 utf8 轉為 unicode
wstring wstr = Utf82Unicode(strUtf8Code);
//最后把 unicode 轉為 ascii
strRet = WideByte2Acsi(wstr);
return strRet;
}
///////////////////////////////////////////////////////////////////////
//ascii 轉 Unicode
wstring Acsi2WideByte(string& strascii)
{
int widesize = MultiByteToWideChar (CP_ACP, 0, (char*)strascii.c_str(), -1, NULL, 0);
if (widesize == ERROR_NO_UNICODE_TRANSLATION)
{
throw std::exception("Invalid UTF-8 sequence.");
}
if (widesize == 0)
{
throw std::exception("Error in conversion.");
}
std::vector<wchar_t> resultstring(widesize);
int convresult = MultiByteToWideChar (CP_ACP, 0, (char*)strascii.c_str(), -1, &resultstring[0], widesize);
if (convresult != widesize)
{
throw std::exception("La falla!");
}
return std::wstring(&resultstring[0]);
}
//Unicode 轉 Utf8
std::string Unicode2Utf8(const std::wstring& widestring)
{
int utf8size = ::WideCharToMultiByte(CP_UTF8, 0, widestring.c_str(), -1, NULL, 0, NULL, NULL);
if (utf8size == 0)
{
throw std::exception("Error in conversion.");
}
std::vector<char> resultstring(utf8size);
int convresult = ::WideCharToMultiByte(CP_UTF8, 0, widestring.c_str(), -1, &resultstring[0], utf8size, NULL, NULL);
if (convresult != utf8size)
{
throw std::exception("La falla!");
}
return std::string(&resultstring[0]);
}
//ascii 轉 Utf8
string ASCII2UTF_8(string& strAsciiCode)
{
string strRet("");
//先把 ascii 轉為 unicode
wstring wstr = Acsi2WideByte(strAsciiCode);
//最后把 unicode 轉為 utf8
strRet = Unicode2Utf8(wstr);
return strRet;
}
