//计算运算符的优先级
int pp(wchar_t c)
{
    int k=-2;
    switch(c){
       case '*':case '/':
                       k=2;
                       break;
       case '+':case '-':
                       k=1;
                       break;
        case '(':case ')':
                        k=0;
                       break;
          case '=':
                    k=-1;
           break;
             }
          return k;
         }

//将字符串转换成实数
double shishu(CString *s,int *k)
{
       double x,y=1.0;
       int flag=1;
       x=0.0;
       wchar_t c=s->GetAt(*k);
       while(c>='0'&&c<='9'||c=='.')
       {
           *k=*k+1;
           if(c>='0'&&c<='9')
            if(flag==0)
            {
                   y*=0.1;
                   x+=(y*(c-48));
            }
            else
                      x=10*x+(c-48);
              else flag=0;
              c=s->GetAt(*k);
             }
          return x;

  }

double GetResult(CString str,CString str1=NULL){
 //格式化str

          int i=0;
 while(0!=str.Replace(L"Ans",str1));
 while(str.GetAt(i)==L'-'){
        if(i==0)
        {
         str.Insert(str.Find(L'-'),L'0');
          }
        else if(str.GetAt(i-1)==L'(')
              str.Insert(i,L'0');
          }

          i=0;
       while(str.GetAt(i)!=L'='){
        switch(str.GetAt(i))
        {
           case L'÷':
                     str.Delete(i);
                     str.Insert(i,'/');
                        break;
           case L'×':
                        str.Delete(i);
                     str.Insert(i,'*');
                        break;
              case L' ':
            str.Delete(i);
               break;
           }

        i++;
 }
//格式化结束

 stack<double>st_data;
 stack<wchar_t>st_op;
 st_op.push('=');
 

       int flag=1,k;

       k=0;
       double x,y;
       wchar_t c=str.GetAt(k);

    while(flag)
 {
        if(c>=L'0'&&c<=L'9'||c==L'.')
         st_data.push(shishu(&str,&k));
        else if(c==L'('||pp(c)>pp(st_op.top()))
        {
               st_op.push(c);
                  k=k+1;
        }
           else if((c==L'=')&&(st_op.top()==L'='))
                  flag=0;
              else if((c==L')')&&(st_op.top()==L'('))
        {
            st_op.pop();
               k++;
           }
           else if(pp(c)<=pp(st_op.top()))
        {
         y=st_data.top();
         st_data.pop();
         x=st_data.top();
         st_data.pop();
         c=st_op.top();
         st_op.pop();
   switch(c)
   {
         case L'+':
                x=x+y;
                break;
         case L'-':
                x=x-y;
                break;
         case L'*':
                x=x*y;
                break;
         case L'/':
                x=x/y;
                break;   
         }
      st_data.push(x);
     }
     c=str.GetAt(k);
    }
 return st_data.top();
}