It’s the null conditional operator. It basically means: “Evaluate the first operand; if that’s null, stop, with a result of null. Otherwise, evaluate the second operand (as a member access of the first operand).” In your example, the point is that if a is null, then a?.PropertyOfA will evaluate to null rather than throwing an exception – it will then compare that null reference with foo (using string’s == overload), … Read more
Take a look at System.IO.File.Move, “move” the file to a new name.
Use a lambda expression Note: C# has a built-in syntax for properties. Instead of writing getter and setter as ordinary methods (as you might be used to from Java), write value is a contextual keyword known only in the set accessor. It represents the value assigned to the property. Since this pattern is often used, C# … Read more
Please use the attributes from the System.Web.Http namespace on your WebAPI actions: The reason why it doesn’t work is because you were using the attributes that are from the MVC namespace System.Web.Mvc. The classes in the System.Web.Http namespace are for WebAPI.
As suggested here this is what you should do: You may get this error when trying to browse an asp.net application. The debug information shows that “This error can be caused by a virtual directory not being configured as an application in IIS.” However, this error occurs primarily out of 2 scenarios. When you create an new … Read more
this will never work. OnTriggerEnter needs a Collider not an Collision. Try this:
How to perform left outer join in C# LINQ to objects without using join-on-equals-into clauses? Is there any way to do that with where clause? Correct problem: For inner join is easy and I have a solution like this but for left outer join I need a solution. Mine is something like this but it’s not working where JoinPair is a … Read more
ou need to find out from the application pool for the website what is the identity it is running under (by default this is Application Pool Identity) and grant that the correct permissions.
I’m currently using a single query in two places to get a row from a database. The query is fine when retrieving the row to put data in to the text boxes, but it returns an error “Sequence contains no elements” when used to retrieve the row in order to edit it and put it … Read more
You can always switch to To provide the default (false), or the value of the boolean column from the database. Or you can specify the default with an overload. Either way, the nullable currently doesnt have a value, which is why you get that exception.