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c#genericsllblgenpro

can't pass default comparer as IComparer<object>

I'm trying to call a "Sort" method that expects a parameter of type IComparer<object>, using the code:

collection.Sort((IComparer<object>)Comparer<DateTime>.Default)

It builds but at run time I get an InvalidCastException with the message:

Unable to cast object of type
'System.Collections.Generic.GenericComparer`1[System.DateTime]'
to type 'System.Collections.Generic.IComparer`1[System.Object]'.

Now what?

Solution

  • If all you want is the default comparison, this will work:

    collection.Sort(Comparer<object>.Default)

    Comparer.Default uses your objects' inherent comparison semantics (i.e., IComparable.CompareTo).