Delphi动态创建组件，并释放内存

unit Unit1;
 
interface
 
uses
  Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
  Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Vcl.ExtCtrls;
 
type
  TForm1 = class(TForm)
    Panel1: TPanel;
    Button1: TButton;
    Edit1: TEdit;
    Memo1: TMemo;
    Button2: TButton;
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
  private
    { Private declarations }
    function getmaxval(myarray: array of Integer):Integer;
  public
    { Public declarations }
  end;
 
var
  Form1: TForm1;
 
implementation
 
{$R *.dfm}
 
var
  rec: Integer = 0;
 
procedure TForm1.Button1Click(Sender: TObject);
var
  i,j,m,n,p:Integer;
  edt: TEdit;
  arr: array of Integer;
begin
  Inc(rec);  //按钮点击次数
  m := 0;
  n := 0;
  p := 0;
  Memo1.Clear;
  for i := 0 to Panel1.ControlCount - 1 do
  begin
    if Panel1.Controls[i] is TEdit then
    inc(m);  //记录edit个数
  end;
  SetLength(arr,m);
  Memo1.Lines.Add('创建组件前的记录:' + #13#10 + '--------------------------');
  Memo1.Lines.Add('Edit组件个数:' + IntToStr(m) + #13#10 + '--------------------------');
  for j := 0 to Panel1.ControlCount - 1 do
  begin
    if Panel1.Controls[j] is TEdit then
    begin
      if n <= m then
      begin
        arr[n] := TEdit(Panel1.Controls[j]).Top;
        Memo1.Lines.Add('Edit' + IntToStr(n + 1) + '的Top值:' + IntToStr(arr[n]));
        Inc(n);
      end else Break;
    end;
  end;
  p := getmaxval(arr); //记录panel里最下面的edit的top值
  Memo1.Lines.Add('最大Top值:' + inttostr(p));
  //动态创建Edit
  //TEdit.Create()，参数是一个AOwner: TComponent，只要是窗体上的组件都可以，
  //但必须要在创建后重新指明父组件的名称，否则没法显示
  edt := TEdit.Create(Panel1);  //指明了owner，可以不释放内存，窗口关闭时由父组件销毁
  edt.Parent := Panel1;
  edt.Left := Edit1.Left;
  edt.Top := p + Edit1.Height + 3;
  edt.Width := Edit1.Width;
  edt.Height := Edit1.Height;
  edt.Text := 'Edit' + IntToStr(rec + 1);
  edt.Show;
end;
 
procedure TForm1.Button2Click(Sender: TObject);  //释放内存，并初始化
var
  i,j,m:Integer;
  edts: array of TEdit;
begin
  j := 0;  //数组edts的键[key]
  SetLength(edts,rec + 1);  //button1次数 + 原有的edit1
  for i := 0 to Panel1.ControlCount - 1 do
  begin
    if Panel1.Controls[i] is TEdit then
    begin
      edts[j] := TEdit(Panel1.Controls[i]);
      Inc(j);
    end;
  end;
  for m := Length(edts) downto 1 do  //edit1不释放，注意此处的downto，根据栈后进先出原则，否则会报错
  begin
    try
      edts[m].Free;
      rec := 0;
      Memo1.Clear;
    except
      //ShowMessage('释放动态创建组件的内存失败！');
    end;
  end;
end;
 
function TForm1.getmaxval(myarray: array of Integer):Integer;  //遍历数组取得最大值
var
  i,max:Integer;
begin
  max := myarray[0];
  for i := 1 to Length(myarray) - 1 do
  begin
    if myarray[i] >= max then
    max := myarray[i];
  end;
  Result := max;
end;
 
end.