using System;

public class Program

{

    public static void Main()

    {

        var orderTypes = " Standard  ,PurchaseOrder, WhatIsThis,ReturnOrder";

        // 1st solution

        if (Enum.TryParse(typeof(TypeEnum), orderTypes, out var enumOrderTypes))

        { }

        Console.WriteLine("1st: " + enumOrderTypes);

        // 2nd solution

        var typeList = orderTypes.Split(',', StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries);

        TypeEnum enumOrderTypes2 = TypeEnum.None;

        foreach (var strType in typeList)

        {

            if (Enum.TryParse(typeof(TypeEnum), strType, out var enumType))

            {

                enumOrderTypes2 |= (TypeEnum)enumType;

            }

        }

        Console.WriteLine("2nd: " + enumOrderTypes2);

    }

}

​

[Flags]

public enum TypeEnum

{

    None = 0,

    Standard = 1 << 0,

    SaleOrder = 1 << 2,

    PurchaseOrder = 1 << 3,

    TransferOrder = 1 << 4,

    ReturnOrder = 1 << 5,

}