VC 计算CString 里的汉字个数

int GetUNum(CString s_instr)
{
 int length = s_instr.GetLength();
 if(length == 0)
  return length;
 int num = 0;
 for(int i = 0;i<length;i++)
 {
  byte c = s_instr[i];
  if(c >= 0xa1 && c <= 0xfe)
  {
   if(i+1>=length)
    break;

   c = s_instr[i+1];
   if(c >= 0xa1 && c <= 0xfe)
   {
    num++;
    i++;
    continue;
   }
  }
 }
 return num;

}