I was asked in an interview how to return Null from a method with integer, double type, etc, without any output parameter.
3 Answers
You can do something like this.
You have to make int type nullable first. by using int?
normally the int datatype in c# are not nullable by default so you have to explicitly convert the int //not nullable type to int? //nullable
You can do the same thing with double etc..
// the return-type is int?. So you can return 'null' value from it.
public static int? method()
{
return null;
}
You can also write the above method in this way:
// this is another way to convert "non-nullable int" to "nullable int".
public static Nullable<int> method()
{
return null;
}
4 Comments
Rand Random
Try it yourself. ?Rand Random
I thought you wanted to post a link to eg. dotnetfiddle, but forgot about the link or so.
Impostor
anyone else here who was trying to click on
Try it yourself?
Rehan Shah
Sorry...i write that but now i delete it...because it was a bit confusing ithink.☺️
If the purpose is to return null value from a function whose return type is int then you can do something like this:
public static int method()
{
Nullable<int> i = null;
if (!i.HasValue)
throw new NullReferenceException();
else
return 0;
}
public static void Main()
{
int? i = null;
try
{
i = method();
}
catch (NullReferenceException ex)
{
i = null;
}
finally
{
// null value stored in the i variable will be available
}
}
Comments
You would have to declare your return type as a nullable int. That way you can return an Int or null. See example below:
private int? AddNumbers(int? First, int? Second)
{
return First + Second;
}
1 Comment
Impostor
How about
private int? GetNull(){ return null;}
int?(which is the same asNullable<int>) Consuming code would then needs to handle it differently, since the return type has changed.