C # - short check for zero

Question

How to replace the following code

if (customer.Person!=null)
 Console.WriteLine(customer.Person.Name);

with something like this

Console.WriteLine(customer.Person.Name?? "unknown");

Answer 1

You can't, I'm afraid there is nothing like Groovy's null-safe dereference operator :(

I suppose you could create a "null object" for Person - that is, a real instance, but with all the null properties. Then you can use:

Console.WriteLine((customer.Person ?? Person.Null).Name ?? "Unknown");

... but it's pretty terrible. (It also does not verify that the value customeris null.)

Another option is to write an extension method for Person:

public static string NameOrDefault(this Person person, string defaultName)
{
    return person == null ? defaultName : person.Name ?? defaultName;
}

Then:

Console.WriteLine(customer.Person.NameOrDefault("Unknown");

Answer 2

You can use the thermal operator :

Console.WriteLine(customer.Person != null ? customer.Person.Name : "unknown");

Not the most beautiful code, but still single-line.

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: IsNullOrWhiteSpace, .