Lucene.net
// Ensures index backward compatibility
const LuceneVersion AppLuceneVersion = LuceneVersion.LUCENE_48;
// Construct a machine-independent path for the index
var basePath = Environment.GetFolderPath(
Environment.SpecialFolder.CommonApplicationData);
var indexPath = Path.Combine(basePath, "index");
using var dir = FSDirectory.Open(indexPath);
// Create an analyzer to process the text
var analyzer = new StandardAnalyzer(AppLuceneVersion);
// Create an index writer
var indexConfig = new IndexWriterConfig(AppLuceneVersion, analyzer);
using var writer = new IndexWriter(dir, indexConfig);