using System.Linq.Expressions;
using System.Collections.Generic;
using System.ComponentModel.DataAnnotations;
using System.ComponentModel;
using System.Text.RegularExpressions;
public static void Main()
List<string> ClientCodes = new List<string>(){"TSO","10C","10B"};
List<string> Payload = new List<string>(){"10C.1.2.3.4","10B.1.2.3.5"};
foreach(var payload in Payload)
var cstring = payload.Split('.')[0];
Console.WriteLine(cstring);
if(ClientCodes.Contains(cstring, StringComparer.OrdinalIgnoreCase))
Console.WriteLine($"{payload} is true");