C# testing for null values

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Active 5 years, 5 months ago. Viewed 6k times. Subtree; searcher. Add "givenName" ; searcher. ToString ;. StevenL StevenL 43 1 1 silver badge 3 3 bronze badges. Add a comment. Active Oldest Votes. But won't that fail if usr. Properties["telephoneNumber"] is null? Jim Mischel - No.

It's never null. Look at my usr. I thought the same as the rest of the answers until I tested it myself. Properties[] would actually return null. Ahhh, I see. It returns an empty collection if the property doesn't exist.

I need to wake up. You said that explicitly in your response. If not exists telephoneNumber , how-to add it properties with null value? Properties["telephoneNumber"]; textBoxFirstName. Since C version 7 you can use the is keyword for the null check like in the snippet below:.

Discards were also introduced. In combination with the Null-coalescing operator?? I think the is keyword is very clear and readable. It is my favorite. You can read more about this in this blog post. With C 9. Before C 9. But the statements above are neither very readable nor easy to understand. But since C 9.

So, with C 9. Thomas Claudius Huber. If there is a need to represent the possible abscence of a value I prefer the Option type. Unfortunately all NRTs bring to the table are compile-time checks that you are putting your null-guards in :. Thanks Thomas. I had the following piece of code that does a null check within a Ternary Expression:. Empty : attribute.

The compiler explained to me that I am trying to do a null check against a non-nullable value type. By attempting this, I realized the null check was not necessary after confirming the type System. CustomAttributeTypedArgument is a non-nullable struct. ObjectModel; using System. Linq; using System. Expressions; using System.

Can't determine non-nullable parameters. ConstructorArguments[ 0 ].