C# equivalent of sql server's IsNull() function

Question

In sql server you can use the IsNull funtion to check if a value is null. I am wondering if there is anything similar in C#, rather than manually checking:

For eg:

myNewValue = IsNull(myValue, new MyValue());

instead of:

if (myValue == null)
  myValue = new MyValue();
myNewValue = myValue;

Thanks.

Answer 1

It's called the null coalescing (??) operator:

myNewValue = myValue ?? new MyValue();

HTH, Kent

Answer 2

Sadly, there's no equivalent to the null coalescing operator that works with DBNull; for that, you need to use the ternary operator:

newValue = (oldValue is DBNull) ? null : oldValue;

Answer 3

For working with DB Nulls, I created a bunch for my VB applications. I call them Cxxx2 as they are similar to VB's built-in Cxxx functions.

You can see them in my CLR Extensions project

http://www.codeplex.com/ClrExtensions/SourceControl/FileView.aspx?itemId=363867&changeSetId=17967

Answer 4

This is meant half as a joke, since the question is kinda silly.

public static bool IsNull (this System.Object o)
{
   return (o == null);
}

This is an extension method, however it extends System.Object, so every object you use now has an IsNull() method.

Then you can save tons of code by doing:

if (foo.IsNull())

instead of the super lame:

if (foo == null)

Answer 5

Very helpful post.