Lazarus Pascal

Enumerate MIME Header Field Names

Demonstrates the Chilkat Mime.GetHeaderFieldName method, which returns the name of the header-field occurrence at a zero-based index. The only argument is the index; use NumHeaderFields for the count. Original order and casing are preserved.

Note: The file path is relative to the application's current working directory. Absolute paths may also be used. Supply the path to your own file.

Background: When you need to walk all the headers — to display them, copy them, or handle duplicates that GetHeaderField would hide — index-based access is the way. NumHeaderFields bounds the loop, and this returns each field's name in its original order and casing, which matters when the exact header sequence is significant.

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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.Mime;

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

procedure RunDemo;
var
  success: Boolean;
  mime: TMime;
  n: Integer;
  i: Integer;
  fieldName: string;

begin
  success := False;

  mime := TMime.Create;
  success := mime.LoadMimeFile('qa_data/message.eml');
  if (success = False) then
    begin
      WriteLn(mime.LastErrorText);
      Exit;
    end;

  //  Iterate the header fields by index.  NumHeaderFields gives the count; GetHeaderFieldName and
  //  GetHeaderFieldValue return the name and value at each zero-based index.  Original order and
  //  casing are preserved.
  n := mime.NumHeaderFields;
  WriteLn('Header fields: ' + n);

  for i := 0 to n - 1 do
    begin
      fieldName := mime.GetHeaderFieldName(i);
      if (mime.LastMethodSuccess = False) then
        begin
          WriteLn(mime.LastErrorText);
          Exit;
        end;
      WriteLn(fieldName);
    end;



  mime.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.