Delphi DLL

Unzip a Text File Entry into a StringBuilder Using ZipEntry.UnzipToSb

See more Zip Examples

This example demonstrates how to use the ZipEntry.UnzipToSb method to inflate a text file entry directly into a StringBuilder object.

The ZIP entry is uncompressed entirely in memory and appended to the StringBuilder without creating a temporary file on disk.

This is useful when:

• Processing text files directly in memory
• Avoiding temporary filesystem files
• Reading configuration files, JSON, XML, CSV, or source code from ZIP archives
• Automatically converting line endings while inflating the text

The srcCharset argument specifies how the uncompressed bytes should be interpreted, such as:

• utf-8
• utf-16
• windows-1252

The lineEndingBehavior argument controls line-ending conversion:

• 0 — Leave line endings unchanged
• 1 — Convert all line endings to bare LF
• 2 — Convert all line endings to CRLF

Suppose the ZIP archive contains:

config/settings.json

The example inflates the JSON file directly into a StringBuilder.

Delphi DLL

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

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Boolean;
zip: HCkZip;
entry: HCkZipEntry;
sb: HCkStringBuilder;
lineEndingBehavior: Integer;
srcCharset: PWideChar;

begin
success := False;

zip := CkZip_Create();

// Open an existing ZIP archive.
success := CkZip_OpenZip(zip,'qa_data/zips/configFiles.zip');
if (success = False) then
  begin
    Memo1.Lines.Add(CkZip__lastErrorText(zip));
    Exit;
  end;

// Locate the JSON file entry within the ZIP archive.
entry := CkZipEntry_Create();

success := CkZip_EntryOf(zip,'config/settings.json',entry);
if (success = False) then
  begin
    Memo1.Lines.Add('ZIP entry not found.');
    CkZip_CloseZip(zip);
    Exit;
  end;

// ------------------------------------------------------------
// Inflate the ZIP entry directly into a StringBuilder.
// 
// The uncompressed text is appended to the StringBuilder.
// 
sb := CkStringBuilder_Create();

// Leave line endings unchanged.
lineEndingBehavior := 0;

// Interpret the uncompressed bytes as UTF-8 text.
srcCharset := 'utf-8';

success := CkZipEntry_UnzipToSb(entry,lineEndingBehavior,srcCharset,sb);
if (success = False) then
  begin
    Memo1.Lines.Add(CkZipEntry__lastErrorText(entry));
    Exit;
  end;

Memo1.Lines.Add('Uncompressed text:');
Memo1.Lines.Add('');
Memo1.Lines.Add(CkStringBuilder__getAsString(sb));

CkZip_CloseZip(zip);

Memo1.Lines.Add('Done.');

CkZip_Dispose(zip);
CkZipEntry_Dispose(entry);
CkStringBuilder_Dispose(sb);

end;