Delphi Byte与数据类型之间的转换

procedure TForm1.FormCreate(Sender: TObject);
type
    TByteArr = array [0..1] of Byte;
    PByteArr = ^TByteArr;
var
  Bytes: TBytes;
  buf,buf2: TByteArr;
  cmd,n_10: string;
  Len: Integer;
  c: char;
  n_int:ushort;
  w:Word;  {Ushort : word}

begin
    cmd:= 'F';
    n_int:= 513;                 {0000 0010 0000 0001 }

    c:= '1';
    Bytes := TEncoding.ASCII.GetBytes(cmd);  {将string类型中的字符转ASCII}
    Len := Length(Bytes);
    cmd:= IntToHex(n_int,2);       {将int类型转出16进制字符串}
    {1}
    Move(n_int,buf,SizeOf(n_int));  {将int 转 Buff}
    {2}
    buf2:= PByteArr(@n_int)^;
end;

procedure TForm1.RzButton1Click(Sender: TObject);
var
  buf: array[0..1] of byte;
  bus: array[0..3] of byte;
  si:SmallInt ;
  i:Integer ;
  w1,w2:Word;    //two bytes represent a word, not an integer
begin                       {定义Byte，并写入数据}
  buf[0] := $01;
  buf[1] := $02;          {0000 0010 0000 0001 }
  bus[0] := $00;
  bus[1] := $01;
  bus[2] := $02;
  bus[3] := $03;
{1}
  Move(buf,si,SizeOf(SmallInt) );
  ShowMessage(IntToStr(si));
{2}
  WordRec(w1).Lo:= buf[0];
  WordRec(w1).Hi:= buf[1];
  w2:= PWORD(@buf)^;
{3}
  Move(bus,i,SizeOf(Integer) );
  ShowMessage(IntToStr(i));
end;

procedure TForm1.RzButton2Click(Sender: TObject);
var
  a: array[0..7] of Byte;
  d1, d2: Double;
begin
  d1 := 123.456;
  fillchar(a, 8, 0);     {fillchar}
  Move(d1, a, 8);
  Move(a, d2, 8);
  ShowMessage(FloatToStr(d2));
end;