[verall]

What I see is two types of people, people that understand basic computer architecture and those that don't.

The C memory model and pointers come easily to those that understand what a memory address is and how long one is on their favorite architecture.

In my experience, people without this knowledge might understand how to use pointers, but not really why they are. And the answer to the "why pointers" question is _not_ "Imagine you want a function that swaps two parameters" nor "because they you would have to copy structs all of the time"

[cogman10]

Honestly, I think the answer to "Pointers, WTF?" is simply describing how data is stored in memory. This concept is important not only for how pointers work but even how data is stored on a hard drive. You don't have to go into great detail. All you need to do is say this is a number, it takes n number of bytes to store (Most people who haven't been living under a rock have a knowledge of bytes, just explain it to them using their phone data plan). Draw a picture showing one set of bytes next to another. Write 0x100 at the first set, 0x100 + number of bytes you put in at the second.

Then, it is simply "0x100 is what's in a pointer".

I don't think that is complex (it shouldn't be). It is intuitive to most. Seeing a picture should solidify things. And finally, it is semi-accurate to how a pointer actually works. Getting into the mud of "A pointer is like a reference in a scholarly paper" or "A pointer is like a link on a webpage" simply confuses what a pointer actually is.

And, if that isn't enough, simply write a program using pointers and print out pointer values. It really is a crazy simple concept that doesn't need a whole lot of metaphors.

What's worse is when the authors of "what's a pointer" don't know what a pointer is themselves. I've seen that far too often.

[verall]

I agree completely.

The correct simplification to make is not explaining virtual memory or MMIO. Pretend we have nicely-acting linear address space. The computer is a mail-sorting octopus and when it runs out of hands it only has mailboxes to put things in. Still not a great analogy.

Everytime I start to hear "addresses are like real addresses, ways to find where something lives" I know it will be an explanation for people that want to understand them well enough to not use them.

It is also rough because some people try to explain pointers with Java. AP CompSci in american high schools is happy to try to explain pointers to Java users, it's not surprising people have a rough time!

[jancsika]

> Pretend we have nicely-acting linear address space.

I feel like the prevalence of linked lists in discussions wrt pointers is proof that nobody is understanding these analogies.

At least there should be some regular pushback from beginners who conceptualize the linear addy space and say, "Hey, what is the distance between this item and the one I just inserted into the list?" Or, "Does it take time to jump around among all these links?"

Edit: And, "How does the time moving among links compare to the time iterating over an array?"

[narag]

Honestly, I think the answer to "Pointers, WTF?" is simply describing how data is stored in memory.

So is this not how it's explained nowadays? No wonder there's people that doesn't get it. So many concepts, not only about programming, I have learnt in my life first with "this is what happens", then with the precise definition...

[Silhouette]

I think part of the problem is that many popular languages now default to using two very different behaviours for elementary tasks like passing variables or parameters around, depending on whether the variable is a "reference type" or a "value type". Simple things like numbers have value semantics. Objects and whatever else works a bit like an object in your language have reference semantics. If you want a reference to a simple value like a number, you box it so the basic type is now wrapped in an object, or something equivalent. Maybe that's even a semi-automatic process that is done for you in some cases. Anyway, that's just how variables work, and the idea that in principle you could have a value of any data type or a reference to any data type doesn't even occur to someone who has learned this way.

Then you get to data structures, and you're trying to explain the fundamental difference between dense, buffer/array-like structures and sparse, graph/pointer-like structures, and there might be no concept of an underlying memory model where the difference is clear.

This has always seemed like a horribly ambiguous and inconsistent mental model to me, and there must surely have been quite a few bugs caused by programmers not clearly understanding the differences between value and reference semantics and exactly when each applies in their chosen language(s). And yet for reasons I can't understand, many of the popular languages today do seem to follow something close to this model.

[narag]

Assembly was fun, but I understand it would be cruel and not so useful to teach it to today students, but I can't figure out how someone can learn some concepts whithout the "memory is an array" model.

My favourite book at college about (the real) data structures started building the array, even if it was already implemented in the language.

[ChrisSD]

I think learning some assembly is essential for any student that wants to use a low level programming language. It's a good way to learn not only about pointers but also the stack, registers, etc. I don't mean they need to be able to manually create a full program in assembly but doing simple exercises can be enlightening on their own.

Of course you also have to mention that even assembly is an abstraction. Memory isn't really a big array, cpus have caches and all that jazz. This matters when writing performant algorithms.

[Silhouette]

It is not necessary to go right down to assembly level to introduce these concepts, though. Just a language with a transparent memory storage model and explicit reference vs value distinction is enough. C is still the lingua franca of the programming world and IMHO it is useful to know basic C for these reasons even if you rarely write much code in it.

[cogman10]

At least in my college days, it didn't seem like it. It felt like a lot of professors jumped straight to the analogies rather than taking a second to just draw things out.

edit that being said, after your comment I went out and looked up "What's a pointer" to see how it is taught. Pretty much every web page I hit does exactly what I described, so, awesome :).

[munchbunny]

Pointers now belong in a weird territory where you can be a perfectly fine programmer without ever having explicitly used a pointer. So most people who have worked with pointers either did it because they cut their teeth on it in school or needed to use C/C++ for hobby/work.