coco2d-x中编码问题。GBK转UTF-8

 由于mac太卡了，在win32下写时，突然发现中文乱码了。没办法，编一个函数转一下。可能以后用得着。

调用：GBKToUTF8(str对象, “gb2312”, “utf-8”);

int GBKToUTF8(std::string & gbkStr, const char* toCode, const char* fromCode){       iconv_t iconvH;       iconvH = iconv_open(fromCode, toCode);       if (iconvH == 0)       {              return -1;       }       const char* strChar = gbkStr.c_str();       const char** pin = &strChar;       size_t strLength = gbkStr.length();       char* outbuf = (char*) malloc(strLength*4);       char* pBuff = outbuf;       memset( outbuf, 0, strLength*4);       size_t outLength = strLength*4;       if (-1 == iconv(iconvH, pin, &strLength, &outbuf, &outLength))       {              iconv_close(iconvH);              return -1;       }       gbkStr = pBuff;       iconv_close(iconvH);       return 0;}