unit Unit1;

interface

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

type
  TForm1 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;
    function GetDiskFreeSpaceEx(lpDirectoryName: PChar;
     var lpFreeBytesAvailableToCaller,lpTotalNumberOfBytes,
         lpTotalNumberOfFreeBytes: LONGLONG): BOOL;
         stdcall; external 'KERNEL32.DLL' name 'GetDiskFreeSpaceExA';

var
  Form1: TForm1;

implementation

{$R *.DFM}

procedure TForm1.Button1Click(Sender: TObject);
var
  FreeBytesAvailableToCaller,
  TotalNumberOfBytes,
  TotalNumberOfFreeBytes : LONGLONG;
begin
  GetDiskFreeSpaceEx(PChar('C:'), FreeBytesAvailableToCaller, TotalNumberOfBytes,
                     TotalNumberOfFreeBytes);

  ShowMessage('총용량 : ' + FormatFloat('#,', TotalNumberOfBytes) +
              ' 바이트, 남은용량 : ' + FormatFloat('#,', TotalNumberOfFreeBytes) +
              ' 바이트');

end;

end.