Memo1内容：
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unit Unit2;

interface

uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls;

type
  TForm2 = class(TForm)
    Memo1: TMemo;
    Memo2: TMemo;
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form2: TForm2;

implementation

{$R *.dfm}

procedure TForm2.Button1Click(Sender: TObject);
var
  I: Integer;
begin
for I := 0 to Memo1.Lines.Count-1 do
begin

if (strtoint(Memo1.Lines.Strings[i])>=5) and (strtoint(Memo1.Lines.Strings[i])<=8) then
begin
  Memo2.Lines.Add(Memo1.Lines.Strings[i]);
end;
end;

end;

end.


结果：
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8