gbk与utf-8转换

linux：

 #include <iconv.h>

 int code_convert(char *from_charset,char *to_charset,char *inbuf,int inlen,char *outbuf,int outlen)
 {
         iconv_t cd;
         int rc;
         char **pin = &inbuf;
         char **pout = &outbuf;

         cd = iconv_open(to_charset,from_charset);
         if (cd==)
                 return -;
         memset(outbuf,,outlen);
         if (iconv(cd,pin,&inlen,pout,&outlen) == -)
                 return -;
         iconv_close(cd);
         return ;
 }

 int u2g(char *inbuf,int inlen,char *outbuf,int outlen)
 {
         return code_convert("utf-8","gb2312",inbuf,inlen,outbuf,outlen);
 }

 int g2u(char *inbuf,size_t inlen,char *outbuf,size_t outlen)
 {
         return code_convert("gb2312","utf-8",inbuf,inlen,outbuf,outlen);
 }

解释：

其中

iconv函数族的头文件是iconv.h,使用前需包含之。
#include <iconv.h>
iconv函数族有三个函数,原型如下:
() iconv_t iconv_open(const char *tocode, const char *fromcode);
此函数说明将要进行哪两种编码的转换,tocode是目标编码,fromcode是原编码,该函数返回一个转换句柄,供以下两个函数使用。
() size_t iconv(iconv_t cd,char **inbuf,size_t *inbytesleft,char **outbuf,size_t *outbytesleft);
此函数从inbuf中读取字符,转换后输出到outbuf中,inbytesleft用以记录还未转换的字符数,outbytesleft用以记录输出缓冲的剩余空间。

() int iconv_close(iconv_t cd);
此函数用于关闭转换句柄,释放资源。

Windows：

     #include <iostream>
     #include <string>
     #include <fstream>
     #include <windows.h>   

     using namespace std;  

     string GBKToUTF8(const std::string& strGBK)
     {
         string strOutUTF8 = "";
         WCHAR * str1;
         int n = MultiByteToWideChar(CP_ACP, , strGBK.c_str(), -, NULL, );
         str1 = new WCHAR[n];
         MultiByteToWideChar(CP_ACP, , strGBK.c_str(), -, str1, n);
         n = WideCharToMultiByte(CP_UTF8, , str1, -, NULL, , NULL, NULL);
         char * str2 = new char[n];
         WideCharToMultiByte(CP_UTF8, , str1, -, str2, n, NULL, NULL);
         strOutUTF8 = str2;
         delete[]str1;
         str1 = NULL;
         delete[]str2;
         str2 = NULL;
         return strOutUTF8;
     }  

     string UTF8ToGBK(const std::string& strUTF8)
     {
         int len = MultiByteToWideChar(CP_UTF8, , strUTF8.c_str(), -, NULL, );
         unsigned short * wszGBK = new unsigned short[len + ];
         memset(wszGBK, , len *  + );
         MultiByteToWideChar(CP_UTF8, , (LPCTSTR)strUTF8.c_str(), -, wszGBK, len);  

         len = WideCharToMultiByte(CP_ACP, , wszGBK, -, NULL, , NULL, NULL);
         char *szGBK = new char[len + ];
         memset(szGBK, , len + );
         WideCharToMultiByte(CP_ACP,, wszGBK, -, szGBK, len, NULL, NULL);
         //strUTF8 = szGBK;
         std::string strTemp(szGBK);
         delete[]szGBK;
         delete[]wszGBK;
         return strTemp;
     }  

     int _tmain(int argc, _TCHAR* argv[])
     {
         string test("我们中国是个强大的名族，强大的动力来自每个人的支持");
         fstream output("test.txt",ios_base::out | ios_base::app);
         output << GBKToUTF8(test);
         //system("iconv -f GBK -t utf-8");
         return ;
     }