Alternative of "??" for non nullable types (e.g. when looking up dictionary keys)

Question

It's very convenient using inline sugar like that: obj?.func(); and obj ?? anotherObj

But I'm trying to find an alternative to the same approach in case I want to pull data from a dictionary without knowing whether the dictionary has the key I'm looking for or not.

Specifically I'd like to do something equivalent to:

someDictionary[someKey] ?? anotherValue such that, if key exists it would use the corresponding value in the dictionary and if not, it will use anotherValue. Obviously it's not possible to use as I wrote it here since it makes no sense, but the idea behind it is sound.

Is there a way to simplify it to be used inline, without making a separate check with if?

It would help if you could give a concrete example including the actual types involved - because that makes it easier to give a concrete example in the answer too. — Jon Skeet, Apr 11 '20 at 13:16
`T obj = dict.TryGetKey(key, out T value) ? value : defaultValue` — Emanuel Vintilă, Apr 11 '20 at 13:17
@JonSkeet in my actual case I simply use as dictionary format. — NewProger, Apr 11 '20 at 13:19
@NewProger: Right, so please include a concrete example *in the question* (not with `enum`, but with a real type). It's so much easier to understand a question when there's a very specific example. — Jon Skeet, Apr 11 '20 at 13:19

score 0 · Accepted Answer · answered Apr 11 '20 at 13:19

0

You can replace if checking with ternary operator

 var value = someDictionary.TryGetValue(someKey, out var val) ? val : anotherValue;

answered Apr 11 '20 at 13:19

Anton

801
4
10

This answer works, but with .NET Core 2+ and C# 7+, this has been implemented in CollectionExtensions. Basically @NewProger only needs to use `var value = someDictonary.GetValueOrDefault(someKey, anotherValue);` – Mark Cilia Vincenti Apr 11 '20 at 14:15
@MarkCiliaVincenti Thanks! I will remember it – Anton Apr 12 '20 at 12:06

Alternative of "??" for non nullable types (e.g. when looking up dictionary keys)

1 Answers1