Lazarus Pascal

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.

Lazarus Pascal

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.StringBuilder,
  Chilkat.Zip;

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

procedure RunDemo;
var
  success: Boolean;
  zip: TZip;
  entry: TZipEntry;
  sb: TStringBuilder;
  lineEndingBehavior: Integer;
  srcCharset: string;

begin
  success := False;

  zip := TZip.Create;

  //  Open an existing ZIP archive.
  success := zip.OpenZip('qa_data/zips/configFiles.zip');
  if (success = False) then
    begin
      WriteLn(zip.LastErrorText);
      Exit;
    end;

  //  Locate the JSON file entry within the ZIP archive.
  entry := TZipEntry.Create;

  success := zip.EntryOf('config/settings.json',entry);
  if (success = False) then
    begin
      WriteLn('ZIP entry not found.');
      zip.CloseZip();
      Exit;
    end;

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

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

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

  success := entry.UnzipToSb(lineEndingBehavior,srcCharset,sb);
  if (success = False) then
    begin
      WriteLn(entry.LastErrorText);
      Exit;
    end;

  WriteLn('Uncompressed text:');
  WriteLn('');
  WriteLn(sb.GetAsString());

  zip.CloseZip();

  WriteLn('Done.');


  zip.Free;
  entry.Free;
  sb.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.