What is the proper way to check for null values?

Question

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,

Answer 1

This is my little type safe "Elvis operator" for versions of .NET that do not support ?.

public class IsNull
{
    public static O Substitute(I obj, Func fn, O nullValue=default(O))
    {
        if (obj == null)
            return nullValue;
        else
            return fn(obj);
    }
}

First argument is the tested object. Second is the function. And third is the null value. So for your case:

IsNull.Substitute(Session["key"],s=>s.ToString(),"none");

It is very useful for nullable types too. For example:

decimal? v;
...
IsNull.Substitute(v,v.Value,0);
....