using System.Text.RegularExpressions; Console.WriteLine(string.Join(Environment.NewLine , Regex .Matches(File.ReadAllText(@"../assets/res/Ln.resx") , "data name=\"(.*?)\"") .Select(x => x.Groups[1].Value) .Where(x => !Directory .GetFiles(@"../src/backend/", "*.cs" , new EnumerationOptions { RecurseSubdirectories = true }) .Select(File.ReadAllText) .Any(y => y.Contains(x))))); Console.ReadKey();