计算器（加了个小数点）。。。[3]

       if s_characterlast='+' then
        begin
            edit1.text:=floattostr(strtofloat(s_number) + strtofloat(edit1.text ));
            s_number:=edit1.text;
            s_characterlast:='-';
            i:='';
       end;

        if s_characterlast='-' then
       begin
            edit1.text:=floattostr(strtofloat(s_number) - strtofloat(edit1.text ));
            s_number:=edit1.text;
            s_characterlast:='-';
            i:='';
       end;

        if s_characterlast='/' then
         begin
             edit1.text:=floattostr(strtofloat(s_number) / strtofloat(edit1.text ));
             s_number:=edit1.text;
             s_characterlast:='-';
            i:='';
         end;
   end
//**************//
    else
        begin
           s_characterlast:='-';
           s_number:=edit1.text;
            i:='432423';
        end;
    j:='3432';
end;

procedure tform1.button14click(sender: tobject);
begin
  s_type:='0';
  if  s='' then

    application.messagebox('请先输入数字','提示:',0)
else
  if  i<>'' then
  begin
        if s_characterlast='x' then
         begin
            edit1.text:=floattostr(strtofloat(s_number) * strtofloat(edit1.text ));
            s_number:=edit1.text;
            s_characterlast:='x';
            i:='';
        end;

       if s_characterlast='+' then
        begin
            edit1.text:=floattostr(strtofloat(s_number) + strtofloat(edit1.text ));
            s_number:=edit1.text;
            s_characterlast:='x';
            i:='';
       end;

        if s_characterlast='-' then
       begin
            edit1.text:=floattostr(strtofloat(s_number) - strtofloat(edit1.text ));
            s_number:=edit1.text;
            s_characterlast:='x';
            i:='';
       end;