procedure myclass.buttonclick(Sender:tobject);
var WinDir:array[0..255]of char;
    i:integer;
begin
 i:=GetWindowsDirectory(WinDir,25); {WinDir is the Windows directory}
  showmessage(WinDir);
end;

mkdir('c:\myapp');       // erstellen
RmDir('C:\MYAPP');  // löschen

var
   DskSpc : Longint;       // vorhandener Speicher
   MinDSpace : Longint; // benötigter
begin
  MinDSpace:=1024000; // Menge des Benötigtem angeben
  DskSpc:=DiskFree(3); // freien Speicher von C(3) lesen
  If DskSpc < MinDSpace then   //freien mit benötigtem vergleichen
           ShowMessage('Not enough Diskspace');
end;

frei := DiskFree(ord(laufwerk) - 64); // "laufwerk" ist ein Char-Typ, z.B.'C'

Var
F : File;
begin
AssignFile(F,'C:\MYAPP\MYAPP.EXE');
Erase(F);
end;

Image1.picture.savetofile('Bild.BMP');

Var
  OutFile : TextFile;
  fname,OutString : string;
begin
  fname:='JUNKFILE.TXT';
  AssignFile(OutFile,fname);
  Rewrite(OutFile);
  OutString:=Edit1.Text;
  Writeln(OutFile,OutString);
  CloseFile(OutFile);
end;

Var
  InFile : TextFile;
  fname,InString : string;
begin
  fname:='JUNKFILE.TXT';
  AssignFile(InFile,fname);
  Reset(Infile);
  Readln(InFile,InString);
  Edit1.Text:=InString;
  CloseFile(InFile);
end;

function istgleich(bm1,bm2:TBitmap):boolean;
var x,y:integer;
p1,p2:PByteArray;
begin
result:=false;
if (bm1.width<>bm2.width)or(bm1.height<>bm2.height)
or(bm1.transparent<>bm2.transparent)      //falls nicht benötigt,löschen
or(bm1.pixelformat<>bm2.pixelformat)then exit;
for x:=0 to bm1.height-1 do begin
p1:=bm1.scanline[x];
p2:=bm2.scanline[x];
for y:=0 to bm1.width-1 do
if p1[y]<>p2[y] then exit;
end;
result:=true;
end;

procedure TForm1.Button2Click(Sender: TObject);
var bm1,bm2:TBitmap;
begin
bm1:=TBitmap.create;
bm2:=TBitmap.create;
bm1.loadfromfile('c:\bilder\corel009.bmp');
bm2.loadfromfile('c:\bilder\corel009.bmp');
if istgleich(bm1,bm2) then showmessage('Die Bilder sind gleich');
bm2.loadfromfile('c:\bilder\corel008.bmp');
if not istgleich(bm1,bm2) then showmessage('Die Bilder sind ungleich');
bm2.free;
bm1.free;
end

function VergleicheTextDateien(datei1,datei2:string):string;
var ts1,ts2:TStringlist;
begin
result:='gleich';
ts1:=TStringlist.create;
ts2:=TStringlist.create;
ts1.loadfromfile(datei1);
ts2.loadfromfile(datei2);
if not ts1.equals(ts2) then result:='un'+result;
ts2.free;
ts1.free;
end;

procedure TForm1.Button4Click(Sender: TObject);
begin
showmessage('Die Dateien sind '+ VergleicheTextDateien('c:\test1.txt','c:\test2.txt'));
end;

function zeitsetzen(datei,datumzeit:string):integer;
var
i:integer;
h:Thandle;
begin
i:=DateTimeToFileDate(StrToDateTime(datumzeit));
h:=FileOpen(datei,fmOpenwrite);
result:=FilesetDate(h,i);
FileClose(h);
end;

procedure TForm1.Button1Click(Sender: TObject);
var s:string;
begin
s:='31.12.2000 17:01:15';
if zeitsetzen('c:\autoexec.bat',s)<>0 then showmessage('Fehler aufgetreten!');
end;

function DiskInDrive(Laufwerk:Char):Boolean;
var SRec:TSearchRec;
    I:Integer;
begin
  Result:=False;
  {$I-}
    I:=FindFirst(Laufwerk+':\*.*',faAnyFile,SRec);
    FindClose(SRec);
  {$I+}
  Case I Of
    0: Result:=True;
    2,18: Result:=True;
  End;
  DiskInDrive:=Result;
end;

function papierkorb(dateien:string):integer;
var sfo:tshfileopstruct;
begin
fillchar(sfo,sizeof(sfo),0);
with sfo do begin
wnd:=application.handle;
wfunc:=fo_delete;
fflags:=fof_noconfirmation or fof_allowundo;
pfrom:=pchar(dateien+#0);
end;
result:=shfileoperation(sfo);
end;

procedure TForm1.Button1Click(Sender: TObject);
var d1,d2,d3,ges:String;
begin
d1:='C:\temp\test1.diz';
d2:='C:\test2.diz';
d3:='C:\test3.diz';
ges:=d1+#0+d2+#0+d3+#0;
papierkorb(ges);
end;

uses DDEMan,...

procedure SearchInFolder(Folder:string);
begin
  with TDDEClientConv.Create(Form1) do begin
    ConnectMode := ddeManual;
    ServiceApplication := 'Explorer.exe';
    SetLink('Folders', 'AppProperties');
    OpenLink;
    ExecuteMacro(PChar('[FindFolder(, '+Folder+')]'), true);
    CloseLink;
    Free;
  end;
end;

NewFileName:=ChangeFileExt(FileListBox1.Filename,'.bak');
if not RenameFile(FileListBox1.Filename,NewFilename) then
  ShowMessage('Umbenennung fehlgeschlagen!');

memo1.Lines.LoadFromFile('test.txt'); // Datei laden

memo1.Lines.SaveToFile('test.txt'); // Datei speichern

interface

uses
Windows, SysUtils, Classes, Menus, ShlObj, Ole2, CommCtrl;

type TShellLinkInfo = record
Error : Boolean;
LinkName : string[255];
Description : string[225];
FileName : string[225];
WorkingDirectory : string[225];
Arguments : string[225];
WindowState : Integer;
HotKey : TShortCut;
IconFileName : string[225];
IconIndex : Integer;
end;

function GetHotKey(AHotKey: Word): TShortCut;
function SetHotKey(AHotKey: TShortCut): Word;
function CreateShellLink(ShellLinkInfo: TShellLinkInfo): Boolean;
function GetShellLinkInfo(LinkName: string): TShellLinkInfo;

implementation

function GetHotKey(AHotKey: Word): TShortCut;
const
Sh: array[Boolean] of TShiftState = ([], [ssShift]);
Ct: array[Boolean] of TShiftState = ([], [ssCtrl]);
Al: array[Boolean] of TShiftState = ([], [ssAlt]);
var
Shift: TShiftState;
begin
Shift := Sh[(Hi(AHotKey) and HOTKEYF_SHIFT = HOTKEYF_SHIFT)]
+ Ct[(Hi(AHotKey) and HOTKEYF_CONTROL = HOTKEYF_CONTROL)]
+ Al[(Hi(AHotKey) and HOTKEYF_ALT = HOTKEYF_ALT)] ;
result := ShortCut(Lo(AHotKey), Shift);
end;

function SetHotKey(AHotKey: TShortCut): Word;
var
Key: Word;
Shift: TShiftState;
begin
ShortCutToKey(AHotKey, Key, Shift);
Key := Swap(Key);
if ssShift in Shift then Key := Key + HOTKEYF_SHIFT;
if ssCtrl in Shift then Key := Key + HOTKEYF_CONTROL;
if ssAlt in Shift then Key := Key + HOTKEYF_ALT;
Key := Swap(Key);
result := Key;
end;

function CreateShellLink(ShellLinkInfo: TShellLinkInfo): Boolean;
var HRes: HResult;
Link: IShellLink;
PerFile: IPersistFile;
str: string;
Buffer: array[0..255] of Char;
HotKey: Word;
Shift: TShiftState;
Size: Integer;
W: PWideChar;

begin
result:=True;

Size:=(Length(ShellLinkInfo.LinkName)+1) * sizeof(WideChar);
GetMem(W, Size);
StringToWideChar(ShellLinkInfo.LinkName, W, Size);

HRes:=CoInitialize(nil);
HRes:=CoCreateInstance(CLSID_ShellLink, nil, CLSCTX_INPROC_SERVER, IID_IShellLink, Link);
if not Succeeded(HRes) then result:=False;

Link.AddRef;

HRes:=Link.QueryInterface(IID_IPersistFile, PerFile);
if not Succeeded(HRes) then result:=False;

//Beschreibung
StrPCopy(Buffer, ShellLinkInfo.Description);
Link.SetDescription(@Buffer);

//Ziel
StrPCopy(Buffer, ShellLinkInfo.FileName);
Link.SetPath(@Buffer);

//Arbeitsverzeichnis
StrPCopy(Buffer, Copy(ExtractFilePath(ShellLinkInfo.FileName), 1, Length(ExtractFilePath(ShellLinkInfo.FileName))-1));
Link.SetWorkingDirectory(@Buffer);

//Argumente
StrPCopy(Buffer, ShellLinkInfo.Arguments); //übergeben eines Parameterstrings
Link.SetArguments(@Buffer);

//FensterStatus
Link.SetShowCmd(ShellLinkInfo.WindowState); //SW_SHOWNORMAL,SW_SHOWMINNOACTIVE,SW_SHOWMAXIMIZED;

//HotKey
Link.SetHotKey(SetHotKey(ShellLinkInfo.HotKey));

//Icon
StrPCopy(Buffer, ShellLinkInfo.IconFileName);
Link.SetIconLocation(@Buffer, ShellLinkInfo.IconIndex); //Bsp.: 0 = erstes (also das Programmicon) der Resource

HRes:=PerFile.Save(W, False);
if not Succeeded(HRes) then result:=False;

Link.Release;
PerFile.Release;
CoUninitialize;

FreeMem(W, Size);
end;

function GetShellLinkInfo(LinkName: string): TShellLinkInfo;
var HRes: HResult;
Link: IShellLink;
PerFile: IPersistFile;
Buffer: array[0..255] of Char;
IntBuffer: Integer;
WordBuffer: Word;
Size: Integer;
W: PWideChar;
Data: TWin32FindData;

begin
result.Error:=False;

Size:=(Length(LinkName)+1) * sizeof(WideChar); GetMem(W, Size);
StringToWideChar(LinkName, W, Size);

HRes := CoInitialize(nil);
HRes := CoCreateInstance(CLSID_ShellLink, nil, CLSCTX_INPROC_SERVER, IID_IShellLink, Link);
if not Succeeded(HRes) then result.Error:=True;

HRes:=Link.QueryInterface(IID_IPersistFile, PerFile);
if not Succeeded(HRes) then result.Error:=True;

HRes := PerFile.Load(W, STGM_READ);
if not Succeeded(HRes) then result.Error:=True;

result.LinkName:=LinkName;

//Beschreibung
Link.GetDescription(@Buffer, MAX_PATH-5);
result.Description := StrPas(Buffer);

//Ziel
Link.GetPath(@Buffer, MAX_PATH-5, Data, SLGP_UNCPRIORITY);
result.FileName := StrPas(Buffer);

//Arbeitsverzeichnis
Link.GetWorkingDirectory(@Buffer, MAX_PATH-5);
result.WorkingDirectory := StrPas(Buffer);

//Argumente
Link.GetArguments(@Buffer, MAX_PATH-5);
result.Arguments := StrPas(Buffer);

//FensterStatus
Link.GetShowCmd(IntBuffer); //SW_SHOWNORMAL, SW_SHOWMINNOACTIVE, SW_SHOWMAXIMIZED
result.WindowState := IntBuffer;

//HotKey
Link.GetHotKey(WordBuffer);
result.HotKey := GetHotKey(WordBuffer);

//Icon
Link.GetIconLocation(@Buffer, MAX_PATH-5, IntBuffer);
result.IconFileName := StrPas(Buffer);
result.IconIndex := IntBuffer;

Link.Release;
PerFile.Release;
CoUninitialize;

FreeMem(W, Size);
end;

end.

Path := ExtractPathFile(ParamStr(0));

Procedure TForm1.Button1Click(Sender: TObject);
Var
FName: TextFile;
S1, S2 : String;
Begin
FName := 'C:\Windows\Win.ini';
Reset(FName);
Readln(FName, S1);
Readln(FName, S2);
Memo1.Lines.Add('One the first line was this text: ' + S1);
Memo1.Lines.Add('One the second line was this text: ' + S2); 
End;

procedure TForm1.Button1Click(Sender: TObject);
var
 f: file;
 l: longint;
 datei, altstring, neustring, s: string;
begin
  altstring := 'Windows 95 wird gestartet...';
  neustring := 'Windows 95 stürzt ab...     ';
  datei := 'C:\kopie von io.sys';

  s := altstring;
  assignFile(f, datei);
  reset(f,1);
  for l := 0 to filesize(f)-length(altstring)-1 do
  begin
   Application.ProcessMessages;
   seek(f,l);
   blockread(f,altstring[1],length(altstring));
   if altstring = s then
   begin
    seek(f,l);
    blockwrite(f,neustring[1],length(neustring));
    label1.caption := 'Status: Stelle gefunden und gepatcht!';
   end;
   Application.ProcessMessages;
  end;
  closeFile(f);
end;

Edit1.Text := ExtractFileName(OpenDialog1.Filename);