UTF-8与GB2312之间的互换

如果您对UTF-8、Unicode、GB2312等还是很陌生的话，请查看http://www.linuxforum.net/books/UTF-8-Unicode.html

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

要实现 GB2312 （其实是GBK）转换为 UTF-8 其实很简单，先用 MultiByteToWideChar 把 GB2312 转换为 Unicode，再用 WideCharToMultiByte 把 Unicode 转换为 UTF-8 就可以了。

UTF-8 转换为 GB2312 是个相反的过程，先用 MultiByteToWideChar 把 UTF-8 转换为 Unicode，再用 WideCharToMultiByte 把 Unicode 转换为 GB2312 就可以了。

给出2个小函数供参考：

// UNICODE to GB2312，即把UNICODE变为普通单字节字符

char *cstring2char(CString str)
{
   int len = str.GetLength();
   int nByte = WideCharToMultiByte(CP_ACP,0,str,len,NULL,0,NULL, NULL );
   char *buf = new char[nByte+1];
   nByte = WideCharToMultiByte(CP_ACP,0,str,len,buf,nByte,NULL, NULL );
   buf[nByte] = '/0';
   char *pchar = _strdup( buf);
   delete buf;

   return pchar;
}

// UNICODE to UTF8，即把UNICODE变为UTF8字符

char *UniCode2UTF8(CString str)
{
   int len = str.GetLength();
   int nByte = WideCharToMultiByte(CP_UTF8,0,str,len,NULL,0,NULL, NULL );
   char *buf = new char[nByte+1];
   nByte = WideCharToMultiByte(CP_UTF8,0,str,len,buf,nByte,NULL, NULL );
   buf[nByte] = '/0';
   char *pchar = _strdup( buf);
   delete buf;

   return pchar;
}