Question

I have a generic list of objects in C#, for example sake, here’s what the object might be.

public class Thing {     public string Name { get; set; }     public DateTime EditDate { get; set; } }  var things = new List<Thing>(); 

Now I want to call:

thing.Sort((t1, t2) => t1.EditDate.CompareTo(t2.EditDate)); 

However, some of my EditDate properties are null. I want these objects with a null EditDate property to show up at the top of my list (i.e. closer to the zero index). How can I do this?

Answer 1

You can create a somewhat more complex lambda, such as:

things.Sort((t1, t2) =>  {  if (t1 == null)  {    return (t2 == null) ? 0 : -1;  }  if (t2 == null)  {    return 1;  }  return t1.EditDate.CompareTo(t2.EditDate); }); 

EndDate cannot be null as it is a value type. However, if you had a specific value of EndDate that you consider as null, you could modify the above code to take that into account in a similar fashion to how I’ve coped with t1 or t2 being null.