I want “(int)null” to return me 0

Question

How can i get 0 as integer value from (int)null.

EDIT 1: I want to create a function that will return me default values for null representa

Answer 1

You can't cast a null to an int, as an int is a value type. You can cast it to an int? though.

What is it you want to achieve?

Answer 2

A method of a generic class that returns nothing works:

 Class GetNull(Of T)
      Public Shared Function Value() As T
           Return Nothing
      End Function
 End Class



 Debug.Print(GetNull(Of Integer).Value())

Answer 3

Use null-coalescing operator or ??

Example:

int? a = null;
return a ?? 0; //this will return 0

It's a new feature in C#. It returns the left-hand operand if the operand is not null; otherwise, it returns the right-hand operand.

Answer 4

You can use the Nullable structure

int value = new Nullable<int>().GetValueOrDefault();

You can also use the default keyword

int value = default(int);

Following 2nd edit:

You need a function that receive any type of parameter, so object will be used. Your function is similar to the Field<T> extension method on a DataRow

public static T GetValue<T>(object value)
{
    if (value == null || value == DBNull.Value)
        return default(T);
    else
        return (T)value;
}

Using that function, if you want an int (and you expect value to be an int) you call it like:

int result = GetValue<int>(dataRow["Somefield"]);

Answer 5

Check out this post for a mostly complete method for writing an extension to do just this. My scenario is pulling data from a NameValueCollection.

http://hunterconcepts.com/blog/Extensions_HttpRequestFormQueryString/

Answer 6

You'll need a return type of Nullable(Of Integer).