substring和slice的区别

unit Unit1;

interface

uses
Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
Dialogs, StdCtrls;

type
TForm1 = class(TForm)
btn1: TButton;
procedure btn1Click(Sender: TObject);
private
{ Private declarations }
public
{ Public declarations }
function Sum (const A: array of Integer): Integer;
end;

var
Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.btn1Click(Sender: TObject);
var
List: array [1..10] of Integer;
X, I: Integer;
begin
// initialize the array
for I := Low (List) to High (List) do
List [I] := I * 2;
// call
X := Sum (List);
ShowMessage(IntToStr(X));
X := Sum (Slice (List, 5));
ShowMessage(IntToStr(X));
end;

function TForm1.Sum (const A: array of Integer): Integer;
var