(Delphi DLL) Remove an Entry from an Existing ZIP Using DeleteEntry

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.

Note: This example requires Chilkat v11.0.0 or greater.

Chilkat for Delphi Downloads Chilkat non-ActiveX DLL for Delphi Chilkat ActiveX DLL for Delphi * The examples here use the non-ActiveX DLL.

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

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Boolean;
zip: HCkZip;
charset: PWideChar;
zip2: HCkZip;
entry: HCkZipEntry;

begin
success := False;

success := False;

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

zip := CkZip_Create();

success := CkZip_NewZip(zip,'original.zip');
if (success = False) then
  begin
    Memo1.Lines.Add(CkZip__lastErrorText(zip));
    Exit;
  end;

charset := 'utf-8';

success := CkZip_AddString(zip,'a.txt','Contents of file A',charset);
if (success = False) then
  begin
    Memo1.Lines.Add(CkZip__lastErrorText(zip));
    Exit;
  end;

success := CkZip_AddString(zip,'b.txt','Contents of file B',charset);
if (success = False) then
  begin
    Memo1.Lines.Add(CkZip__lastErrorText(zip));
    Exit;
  end;

success := CkZip_AddString(zip,'c.txt','Contents of file C',charset);
if (success = False) then
  begin
    Memo1.Lines.Add(CkZip__lastErrorText(zip));
    Exit;
  end;

// Write the ZIP archive to disk.
// 
// The ZIP now contains:
// 
//     a.txt
//     b.txt
//     c.txt
// 
success := CkZip_WriteZipAndClose(zip);
if (success = False) then
  begin
    Memo1.Lines.Add(CkZip__lastErrorText(zip));
    Exit;
  end;

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

zip2 := CkZip_Create();

success := CkZip_OpenZip(zip2,'original.zip');
if (success = False) then
  begin
    Memo1.Lines.Add(CkZip__lastErrorText(zip2));
    Exit;
  end;

// Find the entry named "b.txt".
entry := CkZipEntry_Create();

success := CkZip_EntryOf(zip2,'b.txt',entry);
if (success = False) then
  begin
    Memo1.Lines.Add(CkZip__lastErrorText(zip2));
    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 := CkZip_DeleteEntry(zip2,entry);
if (success = False) then
  begin
    Memo1.Lines.Add(CkZip__lastErrorText(zip2));
    Exit;
  end;

// Write the modified ZIP archive to a new file.
CkZip_putFileName(zip2,'modified.zip');

success := CkZip_WriteZipAndClose(zip2);
if (success = False) then
  begin
    Memo1.Lines.Add(CkZip__lastErrorText(zip2));
    Exit;
  end;

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

Memo1.Lines.Add('ZIP archive updated successfully.');

CkZip_Dispose(zip);
CkZip_Dispose(zip2);
CkZipEntry_Dispose(entry);

end;