перевод из одного типа в другой и по combobox

var a:integer;
      b:extended;
begin
a:=86400000;
b:=a;

var a:integer;
     b:extended;
begin
b:=86400000;
a:=round(a);

unit Unit1;
interface
uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls;
type
  TForm1 = class(TForm)
    ComboBox1: TComboBox;
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;
var
  Form1: TForm1;
  itemscount: integer = 1;
implementation
{$R *.dfm}
procedure TForm1.Button1Click(Sender: TObject);
begin
 ComboBox1.ItemIndex := itemscount;
 itemscount := itemscount+1;
 if itemscount = ComboBox1.Items.Count then
   itemscount := 0;
end;
end.

procedure TForm1.Button2Click(Sender: TObject);
var
x: Extended;
y: Integer;
begin
y := Integer(x);
y := Round(x);//добавьте uses System
y := Ceil(x); //добавьте uses Math
y := Floor(x);//добавьте uses Math
end;

procedure TForm1.Button2Click(Sender: TObject);
var
x: Extended;
y: Integer;
begin
x := 86400000;
//Туда
y := Round(x);//uses System
memo1.Lines.Add(IntToStr(y));
y := Ceil(x); //uses Math
memo1.Lines.Add(IntToStr(y));
y := Floor(x);//uses Math
memo1.Lines.Add(IntToStr(y));
end;
 
procedure TForm1.Button3Click(Sender: TObject);
var
//Обратно
x: Extended;
y: Integer;
begin
y := 86400000;
x := y;
memo1.Lines.Add(FloatToStr(x));
end;
end.

procedure TForm2.ComboBox1Change(Sender: TObject);
begin
case ComboBox1.ItemIndex of
    0: AnalyzeMode(atNone);
 
    1: AnalyzeMode(atSpectrum);
    2: AnalyzeMode(atSpectrumPixel);
    3: AnalyzeMode(atSpectrumMirror);
 
    4: AnalyzeMode(atWave);
    5: AnalyzeMode(atWavePixel);
    6: AnalyzeMode(atWaveStereo);
    7: AnalyzeMode(atWaveMono);
 
    8: AnalyzeMode(atVUMeter);
    9: AnalyzeMode(atVUPixel);
    10: AnalyzeMode(atVUMirror);
 
    11: AnalyzeMode(atCircle);
    12: AnalyzeMode(atCircleStereo);
    13: AnalyzeMode(atCircleMono);
  end;

case i of
0:
1;
.....
end;
i:=i+1;
if i=14 then i:=0;

ComboBox1.ItemIndex := itemscount;
itemscount := itemscount+1;

//Туда
var
x: Extended;
y: Integer;
begin
x := 86400000;
y := Round(x);//uses System
memo1.Lines.Add(IntToStr(y));
//Обратно
var
x: Extended;
y: Integer;
begin
y := 86400000;
x := y;
memo1.Lines.Add(FloatToStr(x));

var
Form1: TForm1;
itemscount: integer = 1;
implementation
{$R *.dfm}
procedure TForm1.Button1Click(Sender: TObject);
begin
 ComboBox1.ItemIndex := itemscount;
 itemscount := itemscount+1;
 if itemscount = ComboBox1.Items.Count then
   itemscount := 0;
end;

 Form2.ComboBox1.ItemIndex := itemscount;
 itemscount := itemscount+1;
 if itemscount = Form2.ComboBox1.Items.Count then
   itemscount := 0;

procedure TForm1.Button1Click(Sender: TObject);
var
   push: boolean;
   i: integer;
begin
i:= 0;
if push then
inc(i);
ComboBox1.ItemIndex:= ComboBox1.ItemIndex + i;
 
if ComboBox1.ItemIndex = ComboBox1.Items.Count - 1 then
begin
dec(i, 13);
  ComboBox1.ItemIndex:= 0;
  inc(i);
  ComboBox1.ItemIndex:= ComboBox1.ItemIndex + i;
end;
 
end;