using System.Text.RegularExpressions;
public static void Main()
var buildNumber = "20230620.18";
const string expression = @"^(?<Year>\d{4})(?<Month>\d{2})(?<Day>\d{2})\.(?<Increment>\d+)$";
var match = Regex.Match(expression, buildNumber, RegexOptions.Compiled | RegexOptions.NonBacktracking);
throw new Exception($"BuildNumber '{buildNumber}' does not match the expected pattern");
var year = match.Groups["Year"];
var month = match.Groups["Month"];
var day = match.Groups["Day"];
var increment = match.Groups["Increment"];
Console.WriteLine($"{year}.{month}.{day}.{increment}");