Aside from what you’d like the precedence to be, what it is according to ECMA, what it is according to the MS spec and what csc actually does, I have one bit of advice: Don’t do this. I think it’s much clearer to write: string c = (a ?? “”) + (b ?? “”); Alternatively, … Read more
This is due to obscure behaviors of Json.NET and the ?? operator. Firstly, when you deserialize JSON to a dynamic object, what is actually returned is a subclass of the Linq-to-JSON type JToken (e.g. JObject or JValue) which has a custom implementation of IDynamicMetaObjectProvider. I.e. dynamic d1 = JsonConvert.DeserializeObject(json); var d2 = JsonConvert.DeserializeObject<JObject>(json); Are actually … Read more
I just found this: The ?? operator aka the Null Coalescing Operator You also have it in C/C++ as a GNU extension using the ?: operator : string pageTitle = getTitle() ?: “Default Title”;
Yes, there is, a long as you’re using VB 9 or later (included with Visual Studio 2008). You can use the version of the If operator overloaded to accept only two arguments: Dim myVar? As Integer = Nothing Console.WriteLine(If(myVar, 7)) More information can be found here in a blog post by the VB.NET team. (Yes, … Read more
I’m tempted to lie and say that English is my second language…but the truth is that I just have no idea what ‘Coalescing’ means. I know what ?? ‘does’ in C#, but the name doesn’t make sense to me. I looked up the word and I understand it to be a synonym for ‘join’. I’d … Read more
When your first argument is null, they’re basically the same except that the null coalescing won’t output an E_NOTICE when you have an undefined variable. The PHP 7.0 migration docs has this to say: The null coalescing operator (??) has been added as syntactic sugar for the common case of needing to use a ternary … Read more
The null coalescing operator has very low precedence so your code is being interpreted as: int? x = 10; string s = (“foo” + x) ?? (0 + “bar”); In this example both expressions are strings so it compiles, but doesn’t do what you want. In your next example the left side of the ?? … Read more
Well, first of all, it’s much easier to chain than the standard ternary operator: string anybody = parm1 ?? localDefault ?? globalDefault; vs. string anyboby = (parm1 != null) ? parm1 : ((localDefault != null) ? localDefault : globalDefault); It also works well if a null-possible object isn’t a variable: string anybody = Parameters[“Name”] ?? … Read more
Thanks to everyone who contributed to analyzing this issue. It is clearly a compiler bug. It appears to only happen when there is a lifted conversion involving two nullable types on the left-hand side of the coalescing operator. I have not yet identified where precisely things go wrong, but at some point during the “nullable … Read more
PHP 7 adds the null coalescing operator: // Fetches the value of $_GET[‘user’] and returns ‘nobody’ // if it does not exist. $username = $_GET[‘user’] ?? ‘nobody’; // This is equivalent to: $username = isset($_GET[‘user’]) ? $_GET[‘user’] : ‘nobody’; You could also look at short way of writing PHP’s ternary operator ?: (PHP >=5.3 only) … Read more