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下面介绍一下WinAPI的两个函数：WideCharToMultiByte、MultiByteToWideChar。函数原型：
int WideCharToMultiByte( UINT CodePage, // code page DWORD dwFlags, // performance and mapping flags LPCWSTR lpWideCharStr, // wide-character string int cchWideChar, // number of chars in string LPSTR lpMultiByteStr, // buffer for new string int cbMultiByte, // size of buffer LPCSTR lpDefaultChar, // default for unmappable chars LPBOOL lpUsedDefaultChar // set when default char used ); //将宽字符转换成多个窄字符 int MultiByteToWideChar( UINT CodePage, // code page DWORD dwFlags, // character-type options LPCSTR lpMultiByteStr, // string to map int cbMultiByte, // number of bytes in string LPWSTR lpWideCharStr, // wide-character buffer int cchWideChar // size of buffer );//将多个窄字符转换成宽字符需要用到的一些函数：
CString CXmlProcess::HexToBin(CString string)//将16进制数转换成2进制 { if( string == "0") return "0000"; if( string == "1") return "0001"; if( string == "2") return "0010"; if( string == "3") return "0011"; if( string == "4") return "0100"; if( string == "5") return "0101"; if( string == "6") return "0110"; if( string == "7") return "0111"; if( string == "8") return "1000"; if( string == "9") return "1001"; if( string == "a") return "1010"; if( string == "b") return "1011"; if( string == "c") return "1100"; if( string == "d") return "1101"; if( string == "e") return "1110"; if( string == "f") return "1111"; return ""; } CString CXmlProcess::BinToHex(CString BinString)//将2进制数转换成16进制 { if( BinString == "0000") return "0"; if( BinString == "0001") return "1"; if( BinString == "0010") return "2"; if( BinString == "0011") return "3"; if( BinString == "0100") return "4"; if( BinString == "0101") return "5"; if( BinString == "0110") return "6"; if( BinString == "0111") return "7"; if( BinString == "1000") return "8"; if( BinString == "1001") return "9"; if( BinString == "1010") return "a"; if( BinString == "1011") return "b"; if( BinString == "1100") return "c"; if( BinString == "1101") return "d"; if( BinString == "1110") return "e"; if( BinString == "1111") return "f"; return ""; } int CXmlProcess::BinToInt(CString string)//2进制字符数据转换成10进制整型 { int len =0; int tempInt = 0; int strInt = 0; for(int i =0 ;i < string.GetLength() ;i ++) { tempInt = 1; strInt = (int)string.GetAt(i)-48; for(int k =0 ;k < 7-i ; k++) { tempInt = 2*tempInt; } len += tempInt*strInt; } return len; } UTF-8转换成GB2312先把UTF-8转换成Unicode.然后再把Unicode通过函数WideCharToMultiByte转换成GB2312WCHAR* CXmlProcess::UTF_8ToUnicode(char *ustart) //把UTF-8转换成Unicode { char char_one; char char_two; char char_three; int Hchar; int Lchar; char uchar[2]; WCHAR *unicode; CString string_one; CString string_two; CString string_three; CString combiString; char_one = *ustart; char_two = *(ustart+1); char_three = *(ustart+2); string_one.Format("%x",char_one); string_two.Format("%x",char_two); string_three.Format("%x",char_three); string_three = string_three.Right(2); string_two = string_two.Right(2); string_one = string_one.Right(2); string_three = HexToBin(string_three.Left(1))+HexToBin(string_three.Right(1)); string_two = HexToBin(string_two.Left(1))+HexToBin(string_two.Right(1)); string_one = HexToBin(string_one.Left(1))+HexToBin(string_one.Right(1)); combiString = string_one +string_two +string_three; combiString = combiString.Right(20); combiString.Delete(4,2); combiString.Delete(10,2); Hchar = BinToInt(combiString.Left(8)); Lchar = BinToInt(combiString.Right(8)); uchar[1] = (char)Hchar; uchar[0] = (char)Lchar; unicode = (WCHAR *)uchar; return unicode; } char * CXmlProcess::UnicodeToGB2312(unsigned short uData) //把Unicode 转换成 GB2312 { char *buffer ; buffer = new char[sizeof(WCHAR)]; WideCharToMultiByte(CP_ACP,NULL,&uData,1,buffer,sizeof(WCHAR),NULL,NULL); return buffer; } GB2312转换成UTF-8：先把GB2312通过函数MultiByteToWideChar转换成Unicode.然后再把Unicode通过拆开Unicode后拼装成UTF-8。
WCHAR * CXmlProcess::Gb2312ToUnicode(char *gbBuffer) //GB2312 转换成 Unicode { WCHAR *uniChar; uniChar = new WCHAR[1]; ::MultiByteToWideChar(CP_ACP,MB_PRECOMPOSED,gbBuffer,2,uniChar,1); return uniChar; } char * CXmlProcess::UnicodeToUTF_8(WCHAR *UniChar) // Unicode 转换成UTF-8 { char *buffer; CString strOne; CString strTwo; CString strThree; CString strFour; CString strAnd; buffer = new char[3]; int hInt,lInt; hInt = (int)((*UniChar)/256); lInt = (*UniChar)%256; CString string ; string.Format("%x",hInt); strTwo = HexToBin(string.Right(1)); string = string.Left(string.GetLength() - 1); strOne = HexToBin(string.Right(1)); string.Format("%x",lInt); strFour = HexToBin(string.Right(1)); string = string.Left(string.GetLength() -1); strThree = HexToBin(string.Right(1)); strAnd = strOne +strTwo + strThree + strFour; strAnd.Insert(0,"1110"); strAnd.Insert(8,"10"); strAnd.Insert(16,"10"); strOne = strAnd.Left(8); strAnd = strAnd.Right(16); strTwo = strAnd.Left(8); strThree = strAnd.Right(8); *buffer = (char)BinToInt(strOne); buffer[1] = (char)BinToInt(strTwo); buffer[2] = (char)BinToInt(strThree); return buffer; } 例子：将GB2312转换成UTF-8的调用：char * CXmlProcess::translateCharToUTF_8(char *xmlStream, int len) { int newCharLen =0 ; int oldCharLen = 0; int revCharLen = len; char* newCharBuffer; char* finalCharBuffer; char *buffer ; CString string; buffer = new char[sizeof(WCHAR)]; newCharBuffer = new char[int(1.5*revCharLen)];//设置最大的一个缓冲区 while(oldCharLen < revCharLen) { if( *(xmlStream + oldCharLen) >= 0) { *(newCharBuffer+newCharLen) = *(xmlStream +oldCharLen); newCharLen ++; oldCharLen ++; }//如果是英文直接复制就可以 else { WCHAR *pbuffer = this->Gb2312ToUnicode(xmlStream+oldCharLen); buffer = this->UnicodeToUTF_8(pbuffer); *(newCharBuffer+newCharLen) = *buffer; *(newCharBuffer +newCharLen +1) = *(buffer + 1); *(newCharBuffer +newCharLen +2) = *(buffer + 2); newCharLen += 3; oldCharLen += 2; } } newCharBuffer[newCharLen] = ''\0''; CString string1 ; string1.Format("%s",newCharBuffer); finalCharBuffer = new char[newCharLen+1]; memcpy(finalCharBuffer,newCharBuffer,newCharLen+1); return finalCharBuffer; }