OperationProgressChanged

public event EventHandler<OperationProgressEventArgs> OperationProgressChanged;

string indexFolder = @"c:\MyIndex\";
string documentsFolder = @"c:\MyDocuments\";

// Creating an index
Index index = new Index(indexFolder);

// Subscribing to the event
index.Events.OperationProgressChanged += (sender, args) =>
{
    Console.WriteLine("Last processed: " + args.LastDocumentPath);
    Console.WriteLine("Result: " + args.LastDocumentStatus);
    Console.WriteLine("Processed documents: " + args.TotalDocuments);
    Console.WriteLine("Progress percentage: " + args.ProgressPercentage);
};

// Indexing documents from the specified folder
index.Add(documentsFolder);