Pascal (Lazarus/Delphi)

Remove an Entry from an Existing ZIP Using DeleteEntry

See more Zip Examples

This example demonstrates how to use the DeleteEntry method to remove a file from an existing ZIP archive.

The example:

• Creates a ZIP archive containing three text files
• Opens the ZIP archive for modification
• Finds and deletes one entry
• Writes the modified ZIP archive to a new filename

Suppose the original ZIP archive contains:

a.txt
b.txt
c.txt

After deleting b.txt, the modified ZIP archive contains:

a.txt
c.txt

The entry is removed only from the in-memory ZIP object until a Write* method is called.

Pascal (Lazarus/Delphi)

program ChilkatDemo;

// Demonstrates using the Chilkat Pascal wrapper via the C bridge DLL.
// Builds as a console application under Lazarus (FPC) or Delphi.

{$IFDEF FPC}
  {$MODE DELPHI}
{$ENDIF}
{$APPTYPE CONSOLE}

uses
  {$IFDEF UNIX}
  cthreads,
  {$ENDIF}
  SysUtils,
  CkDllLoader,
  Chilkat.ZipEntry,
  Chilkat.Zip;

// ---------------------------------------------------------------------------

procedure RunDemo;
var
  success: Boolean;
  zip: TZip;
  charset: string;
  zip2: TZip;
  entry: TZipEntry;

begin
  success := False;

  //  ------------------------------------------------------------
  //  First create a ZIP archive containing three text files.

  zip := TZip.Create;

  success := zip.NewZip('original.zip');
  if (success = False) then
    begin
      WriteLn(zip.LastErrorText);
      Exit;
    end;

  charset := 'utf-8';

  success := zip.AddString('a.txt','Contents of file A',charset);
  if (success = False) then
    begin
      WriteLn(zip.LastErrorText);
      Exit;
    end;

  success := zip.AddString('b.txt','Contents of file B',charset);
  if (success = False) then
    begin
      WriteLn(zip.LastErrorText);
      Exit;
    end;

  success := zip.AddString('c.txt','Contents of file C',charset);
  if (success = False) then
    begin
      WriteLn(zip.LastErrorText);
      Exit;
    end;

  //  Write the ZIP archive to disk.
  //  
  //  The ZIP now contains:
  //  
  //      a.txt
  //      b.txt
  //      c.txt
  //  
  success := zip.WriteZipAndClose();
  if (success = False) then
    begin
      WriteLn(zip.LastErrorText);
      Exit;
    end;

  //  ------------------------------------------------------------
  //  Open the existing ZIP archive for modification.

  zip2 := TZip.Create;

  success := zip2.OpenZip('original.zip');
  if (success = False) then
    begin
      WriteLn(zip2.LastErrorText);
      Exit;
    end;

  //  Find the entry named "b.txt".
  entry := TZipEntry.Create;

  success := zip2.EntryOf('b.txt',entry);
  if (success = False) then
    begin
      WriteLn(zip2.LastErrorText);
      Exit;
    end;

  //  Remove the entry from the in-memory ZIP object.
  //  
  //  At this point, the original ZIP file on disk is unchanged.
  //  The deletion takes effect only after WriteZip or
  //  WriteZipAndClose is called.
  success := zip2.DeleteEntry(entry);
  if (success = False) then
    begin
      WriteLn(zip2.LastErrorText);
      Exit;
    end;

  //  Write the modified ZIP archive to a new file.
  zip2.FileName := 'modified.zip';

  success := zip2.WriteZipAndClose();
  if (success = False) then
    begin
      WriteLn(zip2.LastErrorText);
      Exit;
    end;

  //  The modified ZIP now contains:
  //  
  //      a.txt
  //      c.txt
  //  

  WriteLn('ZIP archive updated successfully.');


  zip.Free;
  zip2.Free;
  entry.Free;

end;

// ---------------------------------------------------------------------------

begin

  try
    RunDemo;
  except
    on E: Exception do
      WriteLn('Unhandled exception: ', E.ClassName, ': ', E.Message);
  end;

  WriteLn;
  {$IFDEF MSWINDOWS}
  WriteLn('Press Enter to exit...');
  ReadLn;
  {$ENDIF}
end.