c++字符集之间转换(UTF-8,UNICODE,Gb2312)

• UTF-8:   3字节一个字符
• UNICODE: 2字节一个字符
• GB2312:  1字节一个字符

例子：
“你”字的UTF-8编码: E4 BD A0　　　　　　　　11100100 10111101 10100000
“你”的Unicode编码: 4F 60　　　　　　　　　   01001111 01100000

按照UTF-8的编码规则，分解如下：xxxx0100 xx111101 xx100000,把除了x之外的数字拼接在一起，就变成“你”的Unicode编码了。
注意UTF-8的最前面３个1，表示整个UTF-8串是由３个字节构成的。
经过UTF-8编码之后，再也不会出现敏感字符了，因为最高位始终为1。

类定义

class CChineseCode{

public:

 

    static void UTF_8ToUnicode(wchar_t* pOut,char *pText);  // 把UTF-8转换成Unicode

    static void UnicodeToUTF_8(char* pOut,wchar_t* pText);  //Unicode 转换成UTF-8

    static void UnicodeToGB2312(char* pOut,wchar_t uData);  // 把Unicode 转换成 GB2312

    static void Gb2312ToUnicode(wchar_t* pOut,char *gbBuffer);// GB2312 转换成　Unicode

    static void GB2312ToUTF_8(string& pOut,char *pText, int pLen);//GB2312 转为 UTF-8

    static void UTF_8ToGB2312(string &pOut, char *pText, int pLen);//UTF-8 转为 GB2312

};

 

//类实现

void CChineseCode::UTF_8ToUnicode(wchar_t* pOut,char *pText){

    char* uchar = (char *)pOut;

    uchar[1] = ((pText[0] & 0x0F) << 4) + ((pText[1] >> 2) & 0x0F);

    uchar[0] = ((pText[1] & 0x03) << 6) + (pText[2] & 0x3F);

    return;

}

 

void CChineseCode::UnicodeToUTF_8(char* pOut,wchar_t* 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] = (0x80 | ((pchar[1] & 0x0F) << 2)) + ((pchar[0] & 0xC0) >> 6);

    pOut[2] = (0x80 | (pchar[0] & 0x3F));

    return;

}

 

void CChineseCode::UnicodeToGB2312(char* pOut,wchar_t uData){

    WideCharToMultiByte(CP_ACP,NULL,&uData,1,pOut,sizeof(wchar_t),NULL,NULL);

    return;

}    

 

void CChineseCode::Gb2312ToUnicode(wchar_t* pOut,char *gbBuffer){

    ::MultiByteToWideChar(CP_ACP,MB_PRECOMPOSED,gbBuffer,2,pOut,1);

    return ;

}

 

void CChineseCode::GB2312ToUTF_8(string& pOut,char *pText, int pLen){

    char buf[4];

    int nLength = pLen* 3;

    char* rst = new char[nLength];

     

    memset(buf,0,4);

    memset(rst,0,nLength);

     

    int i = 0;

    int j = 0;     

    while(i < pLen){

        //如果是英文直接复制就能

        if( *(pText + i) >= 0){

            rst[j++] = pText[i++];

        }else{

              wchar_t 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] = ’’;

    //返回结果

    pOut = rst;            

    delete []rst;    

    return;

}

 

void CChineseCode::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 > 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] = ’’;

        pOut = newBuf;

        delete []newBuf;

        return;

}