System.Randomize Function

Initializes the random number generator with a random value.

Pascal

procedure Randomize;

C++

Randomize();

File

System

Description

Randomize initializes the built-in random number generator with a random value (obtained from the system clock). The random number generator should be initialized by making a call to Randomize, or by assigning a value to RandSeed.

Do not combine the call to Randomize in a loop with calls to the Random function. Typically, Randomize is called only once, before all calls to Random.

Delphi Examples:

Copy Code

{
This example draws many rectangles of various sizes and
colors on a form maximized to fill the entire screen. To run
the code, drop a TTimer component on the form and use the
object inspector to create the OnTimer and OnActivate event
handlers.
}
var
  X, Y: Integer;
procedure TForm1.FormActivate(Sender: TObject);
begin
  WindowState := wsMaximized;
  Timer1.Interval := 50;
  Randomize;
end;

procedure TForm1.Timer1Timer(Sender: TObject);
begin
  X := Random(Screen.Width - 10);
  Y := Random(Screen.Height - 10);
  Canvas.Pen.Color := Random(65535);
  case Random(5) of
    0: Canvas.Pen.Style := psSolid;
    1: Canvas.Pen.Style := psDash;
    2: Canvas.Pen.Style := psDot;
    3: Canvas.Pen.Style := psDashDot;
    4: Canvas.Pen.Style := psDashDotDot;
  end;
  Canvas.Rectangle(X, Y, X + Random(400), Y + Random(400));
end;