计算器（加了个小数点）。。。[4]

        if s_characterlast='/' then
         begin
             edit1.text:=floattostr(strtofloat(s_number) / strtofloat(edit1.text ));
             s_number:=edit1.text;
             s_characterlast:='x';
            i:='';
         end;
   end
//**************//
    else
        begin
           s_characterlast:='x';
           s_number:=edit1.text;
            i:='34342';
        end; 
    j:='3432';
end;

procedure tform1.button15click(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:='/';
            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;

        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:='3432';
        end;
    j:='3432';
end;

procedure tform1.button17click(sender: tobject);
begin
close;
end;

procedure tform1.button16click(sender: tobject);
begin
if s_type='1' then
  if (edit1.text='')   then
  begin
  edit1.text:=edit1.text+'0.';
  s:='123';
  j:=''; end
  else
  begin
  edit1.text:=edit1.text+'.';
  s:='123'; end
else  begin
  if (j<>'') then
  begin
  edit1.text:='';
  edit1.text:=edit1.text+'0.';
   s_type:='1';
  j:='';
  end else
  begin
  edit1.text:='';
  edit1.text:=edit1.text+'.';
  s_type:='1';
  end;
end;
end;