在网上找到了GB2312转化为utf-8的算法：

C/C++ code

void CChineseCodeLib::UTF_8ToUnicode(WCHAR* pOut,char *pText)
{
    char* uchar = (char *)pOut;

    uchar[1] = ((pText[0] & 0×0F) << 4) + ((pText[1] >> 2) & 0×0F);
    uchar[0] = ((pText[1] & 0×03) << 6) + (pText[2] & 0×3F);

    return;
}

void CChineseCodeLib::UnicodeToGB2312(char* pOut,WCHAR *uData)
{
    WideCharToMultiByte(CP_ACP,NULL,uData,1,pOut,sizeof(WCHAR),NULL,NULL);
    return;
}

void CChineseCodeLib::Gb2312ToUnicode(WCHAR* pOut,char *gbBuffer)
{
    ::MultiByteToWideChar(CP_ACP,MB_PRECOMPOSED,gbBuffer,2,pOut,1);
    return;
}

void CChineseCodeLib::UnicodeToUTF_8(char* pOut,WCHAR* pText)
{
    // 注意 WCHAR高低字的顺序,低字节在前，高字节在后
    char* pchar = (char *)pText;

    pOut[0] = (0xE0 | ((pchar[1] & 0xF0) >> 4));
    pOut[1] = (0×80 | ((pchar[1] & 0×0F) << 2)) + ((pchar[1] & 0xC0) >> 6);
    pOut[2] = (0×80 | (pchar[0] & 0×3F));

    return;
}

void CChineseCodeLib::GB2312ToUTF_8(char *pOut,char *pText, int pLen)
{
    char buf[4];
    char* rst = new char[pLen + (pLen >> 2) + 2];

    memset(buf,0,4);
    memset(rst,0,pLen + (pLen >> 2) + 2);

    int i = 0;
    int j = 0;
    while(i < pLen)
    {
        //如果是英文直接复制就可以
        if( *(pText + i) >= 0)
        {
            rst[j++] = pText[i++];
        }
        else
        {
            WCHAR pbuffer;
            Gb2312ToUnicode(&pbuffer,pText+i);

            UnicodeToUTF_8(buf,&pbuffer);

            unsigned short int tmp = 0;
            tmp = rst[j] = buf[0];
            tmp = rst[j+1] = buf[1];
            tmp = rst[j+2] = buf[2];

            j += 3;
            i += 2;
        }
    }
    rst[j] = ‘\0‘;

    //返回结果
    strcpy(pOut,rst);
    delete []rst;

    return;
}

void CChineseCodeLib::UTF_8ToGB2312(string &pOut, char *pText, int pLen)
{
     char * newBuf = new char[pLen];
     char Ctemp[4];
     memset(Ctemp,0,4);

     int i =0;
     int j = 0;

     while(i < pLen)
     {
         if(pText[i] > 0)
        {
            newBuf[j++] = pText[i++];
        }
        else
        {
            WCHAR Wtemp;
            UTF_8ToUnicode(&Wtemp,pText + i);

            UnicodeToGB2312(Ctemp,&Wtemp);

            newBuf[j] = Ctemp[0];
            newBuf[j + 1] = Ctemp[1];

            i += 3;
            j += 2;
        }
     }
     newBuf[j] = ‘\0‘;

     pOut = newBuf;
     delete []newBuf;

     return;
}

用下面的代码段调用

C/C++ code

AnsiString srcStr = "中国加油，奥运加油";
int len = srcStr.Length();
char *dest = new char[len];
CChineseCodeLib *codeLib = new CChineseCodeLib();
codeLib->GB2312ToUTF_8(dest,srcStr.c_str(),len);
TStringList *tSqlList = new TStringList();
tSqlList->Add(dest);
tSqlList->SaveToFile("e:/test.txt");

delete []dest;
delete codeLib;
delete tSqlList;

最后得到的结果为乱码：

涔櫧鍓犳惫锟屽ゥ杈愬墵姹\xB9

是怎么回事呢？是调用不正确还是算法本身有问题？
小弟刚刚学C++，请高手们指点！！

你应该用ansi转UTF-8，不是GB

mark

BCB 有直接的API使用。

Unit

System

Category

character set conversions

extern PACKAGE UTF8String __fastcall AnsiToUtf8(const AnsiString S);

Description

AnsiToUtf8 converts the string specified by S, which uses the ANSI encoding system, to UTF-8.

LZ的做法是错误的;

utf8是针对unicode的另外一种存储方法;

我有现成的代码,已经经过实际使用了,绝对没有问题;

大体的方法是:

GB2312转到unicode,unicode再转utf8;
GB2312转unicode的办法,在CB里面,简单的要死:

AnsiString gb_str = "xxxx";
WideString un_str = gb_str;

wchar_t * pwstr = un_str.b_cstr();//pwstr就是unicode的字串了,每个字符占用2字,0结尾的;

unicode转到utf8,我是借用的linux的NLS_UTF8的内核代码,高效可靠;

如果你需要,我可以发一份给你;