学步园

unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    Button1: TButton;
    Button2: TButton;
    Button3: TButton;
    Button4: TButton;
    Button5: TButton;
    procedure Button1Click(Sender: TObject);
    procedure Button2Click(Sender: TObject);
    procedure Button3Click(Sender: TObject);
    procedure Button4Click(Sender: TObject);
    procedure Button5Click(Sender: TObject);
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

{对字符}
procedure TForm1.Button1Click(Sender: TObject);
var
  C: Char;
begin
  C := 'A';
  C := Char(CharLower(PChar(C)));
  ShowMessage(C); {a}
end;

{对字符常量}
procedure TForm1.Button2Click(Sender: TObject);
var
  C: Char;
begin
  C := Char(CharLower(PChar('A')));
  ShowMessage(C); {a}
end;

{对字符数组}
procedure TForm1.Button3Click(Sender: TObject);
var
  Arr: array[0..2+1] of Char;
begin
  Arr := 'ABC';
  CharLower(Arr);
  ShowMessage(Arr); {abc}
end;

{对字符串}
procedure TForm1.Button4Click(Sender: TObject);
var
  str: string;
begin
  str := 'ABC';
  CharLower(@str[1]);
  ShowMessage(str); {abc}
end;

{Delphi 的 SysUtils.LowerCase}
procedure TForm1.Button5Click(Sender: TObject);
var
  str: string;
begin
  str := 'ABC';
  str := LowerCase(str);
  ShowMessage(str); {abc}
end;

end.