Why is this a Not a legal OleAut date with a TimeSpan of 100 hours and 100 minutes

Question

I'm trying to create a date from a TimeSpan that has 100 hours and 100 minutes but i'm gettin the error:

Run-time exception (line 9): Not a legal OleAut date.

Stack Trace:

[System.OverflowException: Not a legal OleAut date.] at System.DateTime.TicksToOADate(Int64 value)

using System;

public class Program
{
    public static void Main()
    {
        Console.WriteLine("Hello World");
        TimeSpan timeSpan = TimeSpan.FromHours(100) + TimeSpan.FromMinutes(100);
        var OADate = DateTime.FromOADate((DateTime.MinValue.AddTicks(timeSpan.Ticks)).ToOADate());

    }
}

This is to link in with a legacy value in the db from vb6.

It works with small hour and minutes values but fails with this, any ideas?

Created a Fiddle

Answer 1

Let's have a look at the date you are trying to convert into OADate:

TimeSpan timeSpan = TimeSpan.FromHours(100) + TimeSpan.FromMinutes(100);

var OADate = DateTime.MinValue.AddTicks(timeSpan.Ticks);

Console.WriteLine(OADate.ToString("d MMMM yyyy HH:mm:ss", CultureInfo.InvariantCulture));

You'll get this

5 January 0001 05:40:00

But according to the manual (bold is mine)

The base OLE Automation Date is midnight, 30 December 1899. The minimum OLE Automation date is midnight, 1 January 0100. The maximum OLE Automation Date is the same as DateTime.MaxValue, the last moment of 31 December 9999.

that's why DateTime.MinValue.AddTicks(timeSpan.Ticks).ToOADate() is illegal (OADate is below the minimum) and you have the exception thrown.