When to use ? instead of null

Question

Can someone explain the difference between:

if(object?.Count > 0){
    //code   
}

and:

if(object != null && object.Count > 0){
    //code   
}

Or are they doing the same thing? Thank you.

The [documentation](https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/operators/null-conditional-operators) describe the semantics pretty well. In particular, no, they are not the same thing in the case where `object` is something complicated, as the null conditional operator only evaluates its target once. — Jeroen Mostert, Jul 13 '18 at 16:58
Think of `object?` as `if (object == null) return null;` - put it all together and you're effectively checking that `object != null` before attempting to call `.Count` on it. Relevant question [here](https://stackoverflow.com/questions/43074622/question-mark-after-session-variable-reference-what-does-that-mean/43074748#43074748). — trashr0x, Jul 13 '18 at 17:05
I used to wonder why people answer in comments, but after getting downvoted for trying to help, I now understand. — Dan Chase, Jul 13 '18 at 17:17

score 1 · Answer 1 · answered Jul 13 '18 at 16:58

1

The question mark is the null-conditional operator (https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/operators/null-conditional-operators). It is shorter and more precise to write if you are using C# 6 or above.

answered Jul 13 '18 at 16:58

reZach

1 Answers1