Who says inserting into a linked list is faster than inserting things into an array? If the array is pre-allocated, or even crazier a c++ vector or c# list<> with an amortizing growth function that only needs to be invoked once or twice, it'll be much faster than inserting a new node in a linked list.

The array/list can be pre-allocated to the size you need and have good cache locality and minimal container overhead -- the linked list will have the overhead of the pointer to the next node (2x for a doubly-linked list) + the type descriptor (if you're using a language like c#, java, python, etc.) per node and data located all over the heap with cache misses everywhere.

<sameCondescendingToneAsParent> If I was asked during an interview why inserting things in a linked list is faster that [sic] inserting things into an array, and I provided an answer that made him blankly stare back at me, would I want to take the job? </sameCondescendingToneAsParent>

Perhaps you're getting a guy switching careers or fields of expertise (web -> system or accounting -> embedded), or someone that just has that gap in their knowledge, or someone that's just having a plain ol' brainfart at that point in time. No need to be as rude as I responded in my third paragraph.

> Who says inserting into a linked list is faster than inserting things into an array? If the array is pre-allocated, or even crazier a c++ vector or c# list<> with an amortizing growth function that only needs to be invoked once or twice, it'll be much faster than inserting a new node in a linked list.

I said insert, not append. What made you assume the question was about inserting at the end? Even if you have a big pre-allocated array, inserting an element somewhere in the middle will still cost you the price of shifting the "tail" of the array to make space for the new element, while the list will not have that cost.

Now you're just being an ass.

What makes you think insert is important anyway? The typical use cases for an array/list are pop, append and indexing. Python's list implementation uses arrays, not linked lists, internally for exactly this reason: indexing being O[1] is more important for most purposes than fast inserts. (http://docs.python.org/faq/design.html#how-are-lists-impleme...)

The purpose of asking this question is to find whether the person who answers understands the subject matter well enough to reason about it and arrive at the correct answer. It doesn't even matter if insert is a typical use case or not; if the candidate knows data structures he won't even think about it.

And what's with the name-calling? Aren't you capable of having a normal, polite discussion?

I know lots of really good programmers who wouldn't necessarily be able to describe the details of linked list algorithms or malloc. They're doing high level stuff with numpy/scipy, or working on web frameworks, and whether they know malloc or not is irrelevant.

You keep talking about "the subject matter" and "programming" like it's one topic. It's not, hence the "you're an ass" comment - you're just repeating your argument ad nauseam and ignoring everything everyone else has to say.

It's possible to be a good programmer without knowing how linked lists work in excruciating detail - get over it.

> * It's possible to be a good programmer without knowing how linked lists work in excruciating detail - get over it.*

It looks like our definitions of "good" and "programmer" are somewhat different.

People used to make similar arguments in favour of assembly language, ie. you can't be a programmer unless you can drill down to the bare metal and make it do backflips/squeeze every last bit of performance out. Now computers are faster, compilers are smarter at optimising and it's only really the case if you're doing hardcore kernel programming or writing a game engine. C, pointers and linked lists are going the same way as computers get faster still: they're not very relevant unless you're coding something in a specific niche.

And I've seen people who were the opposite of what you're saying - people who knew lots about low level C/Assembly stuff, but who couldn't write clean, maintainable high level code to save their life.

But to get back on the original topic - none of that is relevant to learning how to program. Loops, variables, data structures, managing state, functions and classes are more what you want to teach to start with, and are far more relevant to most programmers than malloc or linked lists.

>what malloc is

There is no reason someone who never programmed C would (or should) know what function is used to allocate memory in C.

Fair enough, but don't you think they should at least know that memory is a resource that needs to be allocated and deallocated and how come that they never have to deallocate memory themselves when writing in python?

Not all languages are (or should be) like C, and not all languages require manual memory management.

If they are going to be programming in Python, there's probably no need for them to be familiar with memory management, or the underlying details of the language implementation - the language is there to insulate you (to a greater or lesser extent) from the machine. Later if it becomes useful to learn about memory management in other languages, they could do so if they are moderately intelligent, it's not rocket science or something that you must learn first or not at all.

That is not the same thing as asking about malloc.

I don't think understanding memory mapping has anything to do with data structures. I have no solid understanding of malloc or how it might be implemented, but RedBlackTrees, TernarySearchTress, LinkedLists, Hashtables, etc are all pretty easy to grasp.

Even the nature of a Struct, and how it might be more efficient than an Object, and the difference between a Stack and a Heap... All that's pretty accessible without sitting through a course on the finer workings of malloc.

The memory is there. It provides my byte buckets. I don't need to care much beyond that to be a good web-developer.

Asking most developers about malloc is probably about as relevant as asking about video frame-buffers. For some spaces it's make or break, but for most it's just useless trivia.

I think understanding roughly how Malloc works can be very helpful in pretty much any area where performance becomes important. Without knowing a bit about Malloc it's hard to understand the benefits of SLAB allocators and similar (which are used everywhere from game engines to OS kernels to DBMS etc).

In it's most basic form Malloc basically is a linked list.

There are legitimate reasons for people to learn to program that don't involve being interviewed by you for a job, just as there are legitimate reasons for learning to write that don't involve writing sonnets.

Similarly, there are different ways to come to the knowledge of what malloc is, or why inserting things into a linked list is faster than inserting things into an array.

> Similarly, there are different ways to come to the knowledge of what malloc is, or why inserting things into a linked list is faster than inserting things into an array.

I completely agree with that. It doesn't matter, as long as the knowledge is acquired somehow. I was just pointing out one of such ways.

Not because he couldn't answer these things, but because he'd only done the one intro Python course.

Or the one intro C course, for that matter.

Jobs where those things matter depend on much more than having got your feet wet with C and malloc learned in one intro course. You probably wouldn't have this guy to the phone screen in the first place. Right?

Those questions would be stupid to ask for a Python position, unless there was some need for working with C APIs. Why waste your time and the developer's time?

Much better to asking about relevant things; some common Python library, or why they'd use lists vs. dictionaries vs. sets, or what a generator expression is.

Allow me do disagree. Tomorrow you're going to have a project that uses a different technology, what are you going to do then? Fire everyone and start hiring again? Of course you need at least a few people on your team who know your current technology in depth, but you probably want to make sure they're they understand the basics.

And please note that those questions are not some intricate C specific questions. Memory management is a basic thing (I'm not talking about actual memory allocation algorithms, just things like how to make sure your program doesn't leak). Linked lists are also basic data structures. It's not asking what "volatile" keyword means and when to use it.

So tomorrow we're all going to go back and start programming our web apps in C? Give me a break. Ask the right questions for the position.

Python also does not have memory management or allocation, linked lists or "volatile". Memory management is basic for C and C++, but that's about it.

How about you need your people to make an iOS 4.x compatible app. Oops, suddenly they need Objective C including all its memory management nasties. This is going to be so much harder if you have never seen pure C.

Well then obviously you'd want someone who can deal with C. "DeepDuh" indeed.

But you're talking hypotheticals - I can do that too: if you suddenly need big data then "Oops", you're going to want someone who knows Hadoop or Erlang. If you need to launch a rocket then "Oops" you're going to want an aerospace engineer. But if you're looking for a web dev, then C/Hadoop/Erlang/Aerospace questions are largely a waste of time, and might disqualify candidates who are otherwise fine or who could figure out C given a couple of days.

Bear in mind that the original topic is talking about languages for learning how to program, not languages for iOS development. If iOS apps float the beginner's boat then by all means learn Objective C; their enthusiasm for the field will probably overcome their frustration with C. But I suspect they'd be better off learning Python or similar first, then starting on C.

Hence my original response: it depends. Python is a pretty good choice because it can do well in lots of different fields and is easy to pick up.

Depends entirely on what the job was. If I'm hiring a programmer who is expected to write C for an embedded platform, then I probably wouldn't hire them. If I'm hiring a 3D artist whom is expected to write mel scripts, then I wouldn't care about those things and wouldn't even be asking those questions.

True, but we're talking about hiring a software engineer here.

No, you're talking about hiring a software engineer. The rest of us are talking about: "Learning to program: Why Python?"