Determine if an object is a DateTime and not null as a condition within ternary

user_1624552 0
Viewed 4384

I have an array of objects:

object[] myArray

This array can contain int, string, DateTime data types and so on.

Now I am trying to check if an object within myArray is of type DateTime and not null so I perform below ternary:

string strDate = myArray[pos] != null && myArray[pos].GetType() is typeof(DateTime) ? Convert.ToDateTime(myArray[pos]).ToString("dd/MM/yyyy") : string.Empty;

But I get below error starting from typeof(DateTime):

Only assignment, call, increment, decrement, await, and new object expressions can be used as a statement

visual-studio-2013 .net-4.5 c#
3 Answers

You can use is operator like

Solution with C#7 pattern matching feature

string strDate = (myArray[pos] is DateTime date) ? date.ToString("dd/MM/yyyy"): string.Empty;
user_62998570

You don't need to call to Convert.ToDateTime as you've already done a check to ensure that the object is a DateTime. Also, instead of using the ternary operator you can use the new switch expression along with some pattern matching:

string stDate = myArray[pos] switch
{
    DateTime d => d.ToString("dd/MM/yyyy"),
    _          => string.Empty
};
user_260950

The below approach will work on old C# compilers. I'd strongly suggest moving to VS 2019 though. Your life will become much easier...

var bob = myArray[pos] as DateTime?;
string strDate = bob == null ? string.Empty : bob.Value.ToString("dd/MM/yyyy");
user_340920
Related