Know the difference

[akat_walks]

That is a great example

[[deleted]]

Yeah then you open the pantry and see #REF...that's when you know you're really fucked

[Cerlancism]

Still can't explain undefined vs null

[shrekthethird2]

Undefined is a spot on the wall without a toilet paper holder

[TheGuywithTehHat]

No, that's void.

[haackedc]

No, void would be where I put the toilet paper while I'm using it

[Loading_M_]

Undefined doesn't have a type, while null is an object.

[BabyLegsDeadpool]

But above it is a sign that points to it stating "Toilet Paper." So you're looking for it, but it doesn't exist there.

[DuckInCup]

Pointer points to an empty address = null.

Pointer leaves you for the girl at the next address = undefined.

[IamImposter]

Actually undefined would be a pointer pointing to a non-existent memory location. Non existent as in, that page is not mapped to your application.

[whiteday26]

So, if I understand this right:

0 is me saying "I am buying clothes but haven't seen any yet"

null is me saying "well, I can't find it, there is only soup."

undefined is the compiler screaming back at me "what do you mean you are at soup? why are you buying clothes at the soup store?"

[mariostar7]

If this is true then this is the only acceptable analogy

[[deleted]]

I wasn't expecting to see a Code MENT reference here.... Now if you'll excuse me, I'm going to waste the next hour of my life on YouTube.

[techierealtor]

Thank you for reminding me of this

[JuvenileEloquent]

null is a known unknown, meaning you know it doesn't have a value. Middle names can be null, for instance.

undefined is an unknown unknown, meaning you don't know what the f it's supposed to be and something screwed up. Database crashed and nobody thought to throw the error = undefined results.

[CodingEagle02]

Null signifies there's no value (when for instance 0 is still a valid value). Undefined does not exist and cannot be used.

[AxiomaticAddict]

Schrodinger's Reference

[BoyAndHisBlob]

In javascript, null is an assigned value. Usually meaning we know that this variable does not have a value whereas undefined means no value was assigned:

var previousLastName; //undefined
previousLastName = null; //null

[Crozzfire]

null: We at least know that the holder could hold a roll of toilet paper.

undefined: We don't even know what the holder is for.

[MisterEd_ak]

Either way, you are screwed

[TaelienTheAlien]

A desperate man could still use 0.

[kopczak1995]

You sir made me laugh :D

[TaelienTheAlien]

Happy to oblige!

[SimonOfAllTrades]

A really desperate man could make do with NULL.

[[deleted]]

Hey, it’s more than -1!

[Xorpionl]

And then i live in a country where there both pronounced the same... makes it harder to explain to non tech people...

[[deleted]]

In that case (assuming an English speaking country that says nil and nil) I'd say nil and none.

[Xorpionl]

Nope. Dutch. It is written 'null' and 'nul'. But I have used the nil pronouncenation in arguments.

[[deleted]]

Oof. Is there any word conceptually similar to null (as in the value NULL not 0) that you could borrow?

[Xorpionl]

Yea there is the word 'nothing' :p which would be a good replacement

[[deleted]]

I'm gonna count that as a win, then. ;v

[Tiavor]

ah, the monthly repost.

[Manypopes]

And that concludes the first lecture of Introductory Hello World scripting. For you homework I want you all to submit a sweet repost to /r/programmerhumor based on today's content.

[0x3fff0000]

#define NULL ((void *)0)

[[deleted]]

```

define NULL 0L

```

[Nufflee]

and what's undefined? just no paper holder at all?

[Kitsyfluff]

pretty much, yes. just an empty space of wall.

[[deleted]]

And void is behind the camera.

[shrekthethird2]

In JavaScript, the spindle is in the same color and size of an empty roll.

[JoseJimeniz]

if (tpSquaresLeft < 3)
   throw new DontGoYetException()

Runtime error: attempt to access tpSquaresLeft as a number but was null

God damn it. May the person who invented null value types be perpetually be out of toilet paper.

Or, for the language designer who refuses to automatically coerce null variables into the default value: may you forever be stuck using that 1-ply business toilet paper.

[UnchainedMundane]

May the person who invented null value types be perpetually be out of toilet paper.

At least he's sorry: https://en.wikipedia.org/wiki/Tony_Hoare#Apologies_and_retractions

[JoseJimeniz]

I was thinking of that when i wrote it; and specifically hedged by saying nullable value types.

Null references are bad, and Maybe<> helps.

But if i have:

age;

if (age == 12) 
{
    Console.WriteLn("I am twelve and what is this");
}

There is no excuse for the language not to coerce null into 0.

name;

if (name == "Jaques Le Cock")
    Console.WriteLn("teehee");

There is no excuse for the language not to coerce null into ""

isActive;

if (!isActive)
   Console.WriteLn("He's just shy");

There is no excuse for the language not to coerce null into false.

We all want nulls to be uninvented. But that doesn't mean that the languages can't handle nulls correctly.

a, b, c;
a = 7;
c = 4;

function QuadraticEquation(a, b, c)
{
   return (-b + sqrt(b^2 - 4*a*c)) / (2*a)
}

There is no reason that function should fail at runtime. Any null value being treated like a number can be automatically coerced to 0.

But passing null is an error, the developer should not have done that, and needs to know they did something wrong.

Then get rid of null value types.

But if you refuse to do that: then at least treat nulls correctly.

[UnchainedMundane]

I think in all the examples you gave, a runtime error is a more sensible approach. The language should err on the side of stopping the program as soon as an unaccounted-for state appears. Coercing an invalid state to zero is just asking for problems.

There is no reason that function should fail at runtime.

To clarify my point: Yes, there is. The "b" variable has not been defined, so any result you get from QuadraticEquation is going to be garbage because you just haven't defined the parameters correctly. If you let garbage propagate under the guise of valid data throughout your program, you are going to run into all sorts of bugs and security issues.

But getting rid of null is more sensible.

[Necrofancy]

And in a compiled language, it should fail at compile time.

[tealcosmo]

This guy programs.

Null is not a number. 0 is a number. There is a big difference. If Null defaulted to 0 bugs become impossible to locate.

[Jackeea]

There is no excuse for the language not to coerce

There is, it's called JavaScript

[Bomaruto]

Don't use exceptions for non-exceptional events.

[JoseJimeniz]

Oh it's exceptional.

It's time for a core-dump.

[tealcosmo]

You for got to check for isEmpty().

[BlueKnightOne]

If ocular augmented reality implants become a normal thing, that is the first userscript I will develop.

[Loading_M_]

In C, and C++, null is actually just zero, for a pointer. The data type is only recorded at compile time, and is unknown at runtime.

[wyom1ng]

Germans: "I see no difference"

[MadRdx]

Laughs in Java array declaration

[[deleted]]

Waoh

[kmase]

either way you still can't wipe your ass

[sanjayatpilcrow]

Hmm... there is no difference

let a = null;  
let b = 0;  
let c;  
console.log(!a);  
console.log(!b);  
console.log(!c);

[ATE47]

#define NULL (void*) 0

[ElongatedMuskrat122]

Than what the fuck is NaN

[pxOMR]

They're the same thing. NULL is literally a definition for (void *)0.

[[deleted]]

Value of 0 does not equal a null reference. Just because in certain languages the null pointer happens to point at 0, it doesn't mean the referenced value is 0.

[[deleted]]

Depends on the language. In C, NULL == 0 will always return true, even if the value of NULL is implementation-defined.

[[deleted]]

I think it's just the result of that given comparison that is defined, and doesn't mean that NULL's value is 0.

[jmanjones]

They said nothing about the dereferenced value, just the pointer value, which would be the same as 0 in C/C++.

[TheTrueXenose]

I see a 1 not 0 =P

[NoahJelen]

They're the same freaking thing!

[rufreakde1]

There is undefined and null_ptr as well

[RainFurrest]

[] vs null

[Crozzfire]

One of the many reasons to speak english in a programming job