Never trust a programmer who says he knows C++

http://lbrandy.com/blog/2010/03/never-trust-a-programmer-who-says-he-knows-c/

by skorks • 16 years ago

87 88 16 years ago

stcredzero5• 16 years ago

Odds are, one should never trust a programmer who thinks they know [X]. Odds are they only think they know really know [X], but they haven't gone too much farther than figuring out how to use the library.

mprime5• 16 years ago

Wait, what?

EDIT: This comment literally says "usually if you think you know something, you don't." So I guess I shouldn't apply for a job using language FooBar, since by this guy's rule I probably don't actually know FooBar.

How does this make sense?

bdr• 16 years ago

There are two different definitions of "know" in play. That's all it is.

RyanMcGreal2• 16 years ago

Maybe the idea is that a competent programmer is also humble.

stcredzero5• 16 years ago

Note the comment makes no absolute statement. Note the reference to "odds." This is almost the same idea as: "Remember, most people think they're an above average driver. Also remember, half the people are below average drivers."

It's also along the same lines as, "There's always someone better than you."

Also note the use of "really." "Know" is twice accompanied by the adjective "really." I would've thought this would make it clear that I wasn't talking about "a little knowledge." The odds are that a programmer does have "a little knowledge" about [X].

Given that you, despite claiming to be puzzled didn't try to take "odds" or the frequent use of the adjective into account, I wonder if you are apt to catch details like that. Maybe this would make a good interview question for coders?

elblanco• 16 years ago

Usually, the more you know, the less you know.

icefox• 16 years ago

After finding out what language/library someone is most proficient in I always ask them what they find bad/wrong about that language/library.

aaronbrethorst2• 16 years ago

Amen to that. It's always amazed me how many candidates I've had sputter on something like this. Nothing flips my bozo bit faster than someone claiming a particular language or technology they've supposedly "mastered" is perfect.

frou_dh• 16 years ago

Never trust an old man who says he's stood on the moon

tjarratt• 16 years ago

Guess I'll be taking C++ off my resume then. Wouldn't want to risk having an interviewer think I'm not trustworthy!

gridspy5• 16 years ago

You liar! ;)

jrockway• 16 years ago

I have never met anyone who knows C++. I have also never met a C++ programmer that knew how to program or what OOP was. (Polymorphism? What's that? Tests? What are those?)

neilc• 16 years ago

Sounds like you've just met a lot of bad C++ programmers. Given that most programmers are terrible and there are a LOT of people who claim to be "C++ programmers", I guess that isn't too surprising. People who actually know (sane, modern) C++ are rare.

mprime5• 16 years ago

I'll be upfront in admitting that I loathe C++ just as much the next guy (I can't seem to get away from Lispy languages), but isn't this being a teeny bit ridiculous?

tbrownaw2• 16 years ago

> I have never met anyone who knows C++.

Hello jrockway, nice to meet you. :)

> I have also never met a C++ programmer that knew how to program or what OOP was. (Polymorphism? What's that? Tests? What are those?)

If you understand those, there's a decent chance you're a real programmer rather than a language-specific programmer.

kscaldef• 16 years ago

I agree with the general observation, but it's definitely not the case that C++ is the only language where this happens.

aidenn0• 16 years ago

True, but C++ is a perfect storm for this.

1) There are a lot of nooks and crannies that can bite you in the butt

2) It's cosmetically similar to C and Java so you get a false sense of security (The article points this out).

3) It's popular (same effect for PHP or Java (I took a intro to programming in this language, so I know it!))

4) Due to #1, every decent C++ shop tends to standardize on a subset of the language, with practices that deal with the nooks and crannies of just that subset.

kabdib3• 16 years ago

I have three standard "screener" questions: (a) what's a virtual method, (b) why would you want to have a destructor be virtual, and (c) what's a virtual base class.

Most folks (if they have a head on their shoulders) get A, a lot get B, and C befuddles almost everyone. (There are a few situations where you'd want to use a virtual base class. And if someone replies, "Oh yeah! I use those all the time!" they're probably using /other/ parts of the language that are just as unsavory).

Related to the original discussion: I've found the folks who self-rate themselves (on a scale of 1-10) as nines (and one guy was a ten) are generally bozos. This is independent of the language in question.

Eliezer• 16 years ago

Long as you don't need any honest 9s or 10s for whatever it is you're doing, I guess that's fine.

kabdib3• 16 years ago

Snarky answer: You can easily tell the 9s or 10s because they answer "eight."

Less snarky: They give you evidence, really quick, that they're a 9 or 10. It's not hard to tell.

d0m5• 16 years ago

A better question is: Why do we need to put the archaic virtual keyword in front of a method? Shouldn't non-virtual functions used in an inheritence way be declared as private while the other being automatically virtual ?

Then if he agrees, he's ok. If he gives you more examples of why C++ is archaic, he's great. If he begins talking about non-virtual methods being more optimized than virtual one, thanks him for his time and try to find someone else.

killedbydeath• 16 years ago

Public non-virtual functions may be useful. For example, to provide alternative API functions. Something like:

  virtual public setOrigin(const Point &p);
  public setOrigin(float x, float y) { setOrigin(Point(x,y)); }

Someone inheriting from this class will know that all the customization is in one function.

haberman2• 16 years ago

> If he begins talking about non-virtual methods being more optimized than virtual one, thanks him for his time and try to find someone else.

What's your problem with this answer? Non-virtual methods can be easily inlined, whereas virtual methods (almost always) require:

1. a load (though a hoistable one) from the vtable

2. an indirect branch

3. register re-allocation

4. function call overhead (standard prologue/epilogue)

sorbits2• 16 years ago

What if he makes a case for keeping types as POD when possible? :)

Anyway, it is clear from your comment that you dislike C++ and you prefer to hire people who agree with you that C++ is archaic, that is fine and all, but it doesn’t show in-depth understanding of the language. Explaining why things are as they are does show deep understanding of the language and a desire to learn the dirty details, IMHO a valuable trait.

pmjordan5• 16 years ago

C++ is used in places other than bleeding edge PCs, you know. The impact of a virtual function call is non-trivial on some systems, the most prominent one that springs to mind is the PlayStation 2. Knowing how they work and when to use them is always a good thing. With that sort of attitude you'll only hire people less competent than yourself; you're trying to find more competent people.

tbrownaw2• 16 years ago

Why C# also makes methods non-virtual by default: http://www.artima.com/intv/nonvirtual.html

Other (shorter) commentary: http://stackoverflow.com/questions/814934/why-c-implements-m...

scott_s3• 16 years ago

One of the main design principles behind C++ was "you don't pay for what you don't use." Hence, if you don't want to use polymorhpic member functions, then you don't pay for the overhead.

gridspy5• 16 years ago

I've been using C++ as my primary language for the last 10 years and know what virtual base classes are. I would never use them, Instead I'd avoid diamond inheritance at all costs.

I'd rate myself as a 9 or 10 for language proficiency but perhaps not for certain niches. For example I know comparably little about Win32 or COM (ugh).

However, there are tons of programmers out there who can't program. Faced with a clean slate they would either choke or create an atrocity. If they rated themselves 5/10 then for me to rate myself only 8/10 would be a disservice to myself. The same is true of perhaps 90% of the programmers on HN.

Of course, I can look back at my former self and know that he thought he was awesome but clearly I have surpassed his ability. It only makes sense that there are far greater programmers out there and I have met a few.

kabdib3• 16 years ago

Right. The bit about virtual base classes is to simultaneously find the folks who know what it is, and to get a good feel for their design sense.

"Don't know" is okay, if they're otherwise a strong engineer. "Love them!" is only good if they can justify it. "Yeah, diamond inheritance, avoid that" is pretty much what I'm looking for, though I'm willing to have a serious conversation about their merit.

These are just questions I can get through in a minute or two, to gauge the person quickly.

_sh• 16 years ago

I used to think a good C++ screener question might be: "When would you use the 'nothrow' constant, and when would you have empty 'throws' specifications in method declarations?"

But then I realized this is just getting tricky with C++ arcana, and is unfair. I once read all of Herb Sutter's 'Exceptional C++' series, and they scared me so much that I still get the frights, years on, when contemplating approaching a C++ compiler.

And I used to think I was OK with C++ too. But after Sutter's books I had to accept that, nah, at best I was mediocre. I admire people who can boldly cast out and rapidly prototype a library or something. Or who have the patience to iteratively engineer a Boost library. I will never achieve this, despite once desperately wanting too.

ntoshev• 16 years ago

So you're asking for OOP, no generic programming / templates? I know template metaprogramming magic becomes madness real fast :-)

I tend not to ask direct language questions anymore, everything is related to the code written on the interview. Like, you asked for a function doing something with an array of ints, and when you get the code you say "now, can we have this function work with arbitrary types instead of just int", "what are the constraints about this types", "what happens if it has a copy constructor but no assignment operator" etc.

And I accept everyone knows and uses some subset of the language.

wheels4• 16 years ago

One funny consequence of this effect is that at 20 I listed like 15 programming languages on my resume; at 26 I listed 3.

chasingsparks2• 16 years ago

I've been moving in the same direction. My question: which three?

wheels4• 16 years ago

At that time (4 years ago, last time I did a resume) C++, C and Perl. I wouldn't list Perl now. There are some other languages I've worked more with in the last couple of years that I would only mention only if they were in the "nice to have" section of a job description, and duly noted as only "some familiarity with".

plesn• 16 years ago

Wow, I have to do a resumé and I'm depressed about myself. I'm nearly about to write:

Languages: C, Python, Haskell

Will code for food in Java,C++,C#,Whatever.

jerf2• 16 years ago

I've long since taken C++ off of my resume, because I haven't used it for 10+ years, since I was in school. But because I'm a normal person for a HN reader, I've kept up with the news, and in learning so many other languages at one time or another have a pretty decent idea what's going on. Recently we started hiring for a C++ position, and I was asked to sit in on the interviews. I said that I didn't really know C++, but I do know enough other stuff to keep up.

Or so I thought. Our interviewer handed out a bit of code something like this

  int some_func(int, SomeComplexObject&);


  .. some code context...
  {
     {
         int a = 1;
         SomeComplexObject b = new SomeComplexObject()
         some_func(a, &b);
     }
     if (b = 0) {
         cout >> "Error" >> endl;
     }
   }

or whatever, something like that, and asked what was wrong. People with "years of experience" in C++ would strain and strain to find "the" error. This is of course a steaming pile of errors, the only legal code line is "int a = 1;" and that's redundant (just stick the 1 in the function call).

I don't have C++ on my resume, but after that experience I'm pretty sure I could put it back on without experiencing too much flak.

On that note, if you're into languages I really recommend the C++ FAQ Lite: http://www.parashift.com/c++-faq-lite/ Anybody who can follow that should probably just leave C++ on the resume. We all know C++ is massive, this is an interesting case study in how the massive language interacts with itself.

wheels4• 16 years ago

Though the point caries, out of nerdiness, I'll point out that most lines are in fact legal:

  int some_func(int, SomeComplexObject&);

Perfectly legal function declaration. You can omit variable names in the signature.

  {
    ...
  }

That defines a scope, which is also fine and occasionally used so that variable names can be recycled with other types later on.

  int a = 1;

You claim this is redundant; I'm not sure why

  if (b = 0) {

If there was a variable in scope named b, this would be legal (the one from above isn't), though probably not what's intended since it would always be false as it will contain the value assigned to b. This syntax is however sometimes used for things like:

  if((location = find_something()) != -1) {

All of that said, if somebody claimed "years of C++ experience" and didn't immediately notice loads of errors in this in about 2 microseconds, they're either a horrible programmer or a liar, and in either case you don't want to remotely consider hiring them.

chasingsparks2• 16 years ago

http://en.wikipedia.org/wiki/Dunning%E2%80%93Kruger_effect

billswift• 16 years ago

I have a hard time with names; I generally think of this as "the third quartile effect". Most people self-evaluate themselves as being in the third quartile of ability - the lowest fifty percent overestimate their ability, while the highest quartile tend to underestimate themselves.

gawi• 16 years ago

Never trust a programmer who says he knows C++... Never trust someone who says he knows... Never trust a programmer... Never trust C++ ... Never C++...

At university, they taught me C++. I suffered a lot. So the minute I graduated, I stopped doing it. This was a valuable lesson after all.

If someone pretends to understand C++, just look at his code and say "Ok, so what happens if you add 'volatile' just here."

gridspy5• 16 years ago

And a good programmer will raise his eyebrow at you and coolly reply "a little less optimisation"

jmtulloss• 16 years ago

I'm a C programmer, not a C++ one, but at least in C, you sometimes need volatile to have a correct program.

defen• 16 years ago

I remember well the "static object initialization segfaults" valley.

froo2• 16 years ago

Always trust a graph that has no numbers or points to compare scale!

known• 16 years ago

Do you mean I shouldn't trust http://en.wikipedia.org/wiki/Bjarne_Stroustrup

froo2• 16 years ago

No, just look at that bottom picture. He looks suspiciously a lot like Dr Robotnik (with a shaved moustache)

http://bit.ly/dbWcWv

DanielBMarkham• 16 years ago

Another post that confuses "all the features of C++" with "programming in C++"

Once more for the record, programming in C++ does not involve using all of the features of this massive language. In fact, a good C++ programmer keeps things as brutally simple as possible. C++ programming forces you to.

The author is dead-on about how you get swamped by the features. What he missed is that you come out of the valley on the other side with a good appreciation for "That hurts. Let's not do that unless we absolutely have to"

You know, C++ has to be a significant language. Nowhere else have so many people cried out in pain and frustration. Yet the language still rolls on. That's probably not much of an endorsement! (grin)

VBprogrammer3• 16 years ago

I mostly agree with you but I don't think I'd apply for a job specifically programming in C++ without knowing the appropriate use cases for the majority of the language features. Obviously different if you are only listing it as a language you have some familiarity with.

Retric• 16 years ago

I think you overestimate the value and difficulty in learning the less often used aspects of C++. C++ still includes the asm keyword and in some areas you are going to see it used. However, while I might like people to know at least one ASM language it's far from required to call yourself a C++ programmer.

DCoder• 16 years ago

In my current free time project, I learned enough C++ by reading assembly to not find anything new in Lippman's "C++ Object Model". I'm not sure if that's a good sign or a bad one - did I see so many tricks, was I not reading attentively, or what... pity the book doesn't cover COM+ though.

When I inherited this project, it was relying on (cast)s and macros all around and this led me to some nasty traps, I switched to building a lot of templates, they've so far proven invaluable in saving debugging time, enforcing type safety, and communicating expected data types to other developers. Templates are good. And macros are traps, but everyone already knew that.

Granted, the project is a niche, I don't think there are many similar projects out there, so not sure how useful my knowledge of the object model is. I'm reversing/extending a C++ game with no source, btw. DLL injection and all that goodness.

JoeAltmaier• 16 years ago

You can cut your hand off with a power tool.

Never trust a programmer who says he knows C++

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