Null is the absence of a value. Null is typically used to indicate that a reference or pointer variable points to no object in memory.

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32
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4answers
7k views

Where are null values stored, or are they stored at all?

I want to learn about null values or null references. For example I have a class called Apple and I created an instance of it. Apple myApple = new Apple("yummy"); // The data is stored in memory ...
82
votes
16answers
24k views

Should one check for null if he does not expect null?

Last week, we had a heated argument about handling nulls in our application's service layer. The question is in the .NET context, but it will be the same in Java and many other technologies. The ...
22
votes
10answers
2k views

Are nullable types preferable to magic numbers?

I have been having a little bit of a debate with a coworker lately. We are specifically using C#, but this could apply to any language with nullable types. Say for example you have a value that ...
58
votes
24answers
31k views

How can I explain the difference between NULL and zero?

Working on a problem that uses the percent change formula: percent change = 100 * [(new value - old value) / old value] How would I explain the difference if new value or old value = NULL, rather ...
15
votes
3answers
7k views

Should I store False as Null in a boolean database field?

Let's say you have an application that has a boolean field in its User table called Inactive. Is there anything inherently wrong with just storing false as null? If so can you please explain what the ...
31
votes
7answers
67k views

Why doesn't “object reference not set to an instance of an object” tell us which object?

We're launching a system, and we sometimes get the famous exception NullReferenceException with the message Object reference not set to an instance of an object. However, in a method where we have ...
4
votes
2answers
332 views

Nulls in every type and checked exceptions in Java?

I know that null being added to every type in Java is a source of much frustration regarding the language's type system. At the same time I generally hear complaining about checked exceptions - that ...
6
votes
4answers
7k views

What is the difference between a pointer pointing to 0x0 location and a pointer set to NULL?

Is a pointer pointing to 0x0000 the same as a pointer set to NULL? If NULL value is defined in the C language, then what location does it physically translate to? Is it the same as 0x0000. Where can I ...
11
votes
10answers
1k views

Should security restrictions cause a service to return null or throw an exception? [closed]

I'm in a bit of a disagreement with a more experienced developer on this issue, and wondering what others think about it; our environment is Java, EJB 3, services, etc. The code I wrote calls a ...
20
votes
7answers
9k views

How does throwing an ArgumentNullException help?

Let's say I have a method: public void DoSomething(ISomeInterface someObject) { if(someObject == null) throw new ArgumentNullException("someObject"); someObject.DoThisOrThat(); } I've been ...
20
votes
13answers
3k views

Why are null references shunned while throwing exceptions is considered okay?

I don't quite understand the consistent bashing of null references by some programming language folks. What's so bad about them? If I request read access to a file that doesn't exist then I'm ...
3
votes
2answers
143 views

Best Way to Express Meta-Info on Missing Data?

I work in healthcare IT, reviewing data management processes of various observational studies. One problem I have repeatedly faced is the poorly encoded data, especially when some values are missing. ...
12
votes
11answers
20k views

Best way to handle nulls in Java? [closed]

I have some code that is failing because of NullPointerException. A method is being called on the object where the object does not exist. However, this led me to think about the best way to fix ...
7
votes
10answers
3k views

Property-coalescing operator for C#

The null-coalescing operator in c# allows you to shorten the code if (_mywidget == null) return new Widget(); else return _mywidget; Down to: return _mywidget ?? new Widget(); I ...
4
votes
8answers
2k views

How will you handle NULL values in your application?

At what level do you prefer to handle Null values in your application? My personal preference at the moment is the DB. When I build a view, I ensure that I return a value in place of a NULL value. So ...
55
votes
11answers
73k views

SQL: empty string vs NULL value

I know this subject is a bit controversial and there are a lot of various articles/opinions floating around the internet. Unfortunatelly, most of them assume the person doesn't know what the ...
109
votes
26answers
23k views

Are null references really a bad thing?

I've heard it said that the inclusion of null references in programming languages is the "billion dollar mistake". But why? Sure, they can cause NullReferenceExceptions, but so what? Any element of ...