How to check if one DateTime is greater than the other in C#

Question

I have two DateTime objects: StartDate and EndDate. I want to make sure StartDate is before EndDate. How is this

Answer 1

if (StartDate>=EndDate)
{
    throw new InvalidOperationException("Ack!  StartDate is not before EndDate!");
}

Answer 2

        if (new DateTime(5000) > new DateTime(1000))
        {
            Console.WriteLine("i win");
        }

Answer 3

I had the same requirement, but when using the accepted answer, it did not fulfill all of my unit tests. The issue for me is when you have a new object, with Start and End dates and you have to set the Start date ( at this stage your End date has the minimum date value of 01/01/0001) - this solution did pass all my unit tests:

    public DateTime Start
    {
        get { return _start; }
        set
        {
            if (_end.Equals(DateTime.MinValue))
            {
                _start = value;
            }
            else if (value.Date < _end.Date)
            {
                _start = value;
            }
            else
            {
                throw new ArgumentException("Start date must be before the End date.");
            }
        }
    }


    public DateTime End
    {
        get { return _end; }
        set
        {
            if (_start.Equals(DateTime.MinValue))
            {
                _end = value;
            }
            else if (value.Date > _start.Date)
            {
                _end = value;
            }
            else
            {
                throw new ArgumentException("End date must be after the Start date.");
            }
        }
    }

It does miss the edge case where both Start and End dates can be 01/01/0001 but I'm not concerned about that.

Answer 4

I'd like to demonstrate that if you convert to .Date that you don't need to worry about hours/mins/seconds etc:

    [Test]
    public void ConvertToDateWillHaveTwoDatesEqual()
    {
        DateTime d1 = new DateTime(2008, 1, 1);
        DateTime d2 = new DateTime(2008, 1, 2);
        Assert.IsTrue(d1 < d2);

        DateTime d3 = new DateTime(2008, 1, 1,7,0,0);
        DateTime d4 = new DateTime(2008, 1, 1,10,0,0);
        Assert.IsTrue(d3 < d4);
        Assert.IsFalse(d3.Date < d4.Date);
    }