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unit UpperCaseAndLowerCase;

interface

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

type
  TForm5 = class(TForm)
    lbl1: TLabel;
    edt1: TEdit;
    lbl2: TLabel;
    edt2: TEdit;
    lbl3: TLabel;
    edt3: TEdit;
    procedure edt1Change(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form5: TForm5;

implementation

{$R *.dfm}

procedure TForm5.edt1Change(Sender: TObject);
begin
edt3.Text:= UpperCase(edt1.text);       // 字符串转换成大写
edt2.Text := LowerCase(edt1.Text);     //  字符串转换成小写
end;

end.