null-coalescing-operator

I love the null-coalescing operator because it makes it easy to assign a default value for nullable types. int y = x ?? -1; That's great, except if I need to do something simple with x . For instance, if I want to check Session , then I usually end up having to write something more verbose. I wish I could do this: string y = Session["key"].ToString() ?? "none"; But you can't because the .ToString() gets called before the null check so it fails if Session["key"] is null. I end up doing this: string y = Session["key"] == null ? "none" : Session["key"].ToString(); It works and is better, in my

Is there a null coalescing operator in powershell? I'd like to be able to do these c# commands in powershell: var s = myval ?? "new value"; var x = myval == null ? "" : otherval; No need for the Powershell Community Extensions, you can use the standard Powershell if statements as an expression: variable = if (condition) { expr1 } else { expr2 } So to the replacements for your first C# expression of: var s = myval ?? "new value"; becomes one of the following (depending on preference): $s = if ($myval -eq $null) { "new value" } else { $myval } $s = if ($myval -ne $null) { $myval } else { "new

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'. 'Null Join Operator' still doesn't make sense. Can someone enlighten me? 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

Recently I had a weird bug where I was concatenating a string with an int? and then adding another string after that. My code was basically the equivalent of this: int? x=10; string s = "foo" + x ?? 0 + "bar"; Amazingly enough this will run and compile without warnings or incompatible type errors, as will this: int? x=10; string s = "foo" + x ?? "0" + "bar"; And then this results in an unexpected type incompatibility error: int? x=10; string s = "foo" + x ?? 0 + 12; As will this simpler example: int? x=10; string s = "foo" + x ?? 0; Can someone explain how this works to me? Mark Byers The null

Note: this appears to have been fixed in Roslyn This question arose when writing my answer to this one , which talks about the associativity of the null-coalescing operator . Just as a reminder, the idea of the null-coalescing operator is that an expression of the form x ?? y first evaluates x , then: If the value of x is null, y is evaluated and that is the end result of the expression If the value of x is non-null, y is not evaluated, and the value of x is the end result of the expression, after a conversion to the compile-time type of y if necessary Now usually there's no need for a

Question : The line price = co?.price ?? 0, in the following code gives me the above error. but if I remove ? from co.? it works fine. I was trying to follow this MSDN example where they are using ? on line select new { person.FirstName, PetName = subpet?.Name ?? String.Empty }; So, it seems I need to understand when to use ? with ?? and when not to. Error : an expression tree lambda may not contain a null propagating operator public class CustomerOrdersModelView { public string CustomerID { get; set; } public int FY { get; set; } public float? price { get; set; } .... .... } public async Task