C# Online Compiler | .NET Fiddle

using System;
using System.Globalization;
					
public class Program
{
	public static void Main()
	{
		CultureInfo nlBEFormaat = new CultureInfo("nl-BE");
		
		DateTime Datum = new DateTime(2017, 9, 1);
		
		int iDatum = Datum.Year;
		Datum = Datum.AddDays(5);

		Console.WriteLine(iDatum);		
		Console.WriteLine(Datum.ToString("dd dddd MMMM yyyy", nlBEFormaat));

	}
}

Cached Result

Environment version: .NET 9.0.0 (9.0.0)
System.Text.Json version: System.Text.Json, Version=9.0.0.0, Culture=neutral, PublicKeyToken=cc7b13ffcd2ddd51

Testing deserialization of "" to type System.Nullable`1[System.DateTime]:
   Succeeded, value = null
Testing deserialization of "" to type System.Nullable`1[System.Int32]:
   Succeeded, value = null
Testing deserialization of "" to type System.Nullable`1[System.Double]:
   Succeeded, value = null
Testing deserialization of "" to type System.Nullable`1[System.Decimal]:
   Succeeded, value = null
Testing round-trip of System.Nullable`1[System.DateTime] 06/12/2025 00:22:53
   Passed.
Testing round-trip of System.Nullable`1[System.DateTime]
   Passed.
Testing round-trip of System.DateTime 06/12/2025 00:22:53
   Passed.
Testing round-trip of System.Nullable`1[System.Int32] 1
   Passed.
Testing round-trip of System.Nullable`1[System.Int32]
   Passed.
Testing round-trip of System.Nullable`1[System.Decimal] 1.010101
   Passed.
Testing round-trip of System.Nullable`1[System.Decimal]
   Passed.
Testing round-trip of System.Nullable`1[System.Double] 1.010101
   Passed.
Testing round-trip of System.Nullable`1[System.Double]
   Passed.