from Hacker News

From C to C++: A quick reference for aging programmers

by angelortega on 10/15/11, 7:46 AM with 38 comments

by exDM69 on 10/15/11, 9:02 AM
No no no no. This is not a very good reference or tutorial or even an introduction. It even teaches some bad practices and omits crucial detail.
The biggest problem I saw was that it introduces classes and objects but does not tell you anything about the "rule of 3", destructors, copy constructors and assignment operators. These are crucial to understanding C++'s pass-by-value semantics and writing sensible C++. C++11 adds to this mess by adding rvalue references, move constructors and whatnot. Writing good and safe C++ requires you to use stack based resource management wisely and use ctors/dtors for initialization and cleanup (this is also why you almost never write try/catch in C++ - and there's no finally statement).
Another example: the article shows you how to do a Java-like constructor like this: point::point(int x, int y) { this->x = x; this->y = y; }
When in C++ you want to use initializer lists like this: point::point(int x, int y) : x(x), y(y) {}
At best this tutorial teaches you to write "C/C++" (the worlds most popular programming language that does not exist) or "C with classes". This style of programming has all the disadvantages of writing C but none of the advantages of C++.
C++ is one of the most complicated languages out there, on par with Haskell and Scala. It's C legacy makes it also somewhat dangerous and the pass-by-value semantics make it very different from any other language out there. You cannot expect to learn even a little bit of C++ from little vague blog posts like this.
If you want to learn C++, buy a book! The web is full of crappy resources like this one.
by obiterdictum on 10/15/11, 9:20 AM
This feels like a C++ tutorial from mid-90s. C++ code written today looks nothing like what's presented in this article. Besides, some poor sample code choices jump out at me, like throwing an int and using C library. I realize they are there to illustrate a point, but this reinforces bad habits.
In fact, if you are learning C++, you better start it as a new language, rather than a tumor grown on the side of C. These languages are too idiomatically different.
by AshleysBrain on 10/15/11, 4:08 PM
Seems to be missing some important points:
const methods - if you declare a const rectangle r, you can't call r.surface() unless it's declared int surface(void) const {....
references - article seems to be confused why they exist. They enable some extra handy features, e.g. you can pass a temporary to a function parameter taking a const reference. e.g. you can pass f(MyClass()) if it's declared void f(const MyClass&), but not if it's declared void f(const MyClass*).
STL - things like std::string, std::vector, std::map - totally invaluable!
And lastly, the fact that programming in C++ is completely different to C. It's not like C with bolted on features. It's a whole new paradigm. For example, in modern C++, you very rarely have to manage memory. Smart pointers and containers can generally manage it all for you.
by js2 on 10/15/11, 12:30 PM
Here's a first aid kit for when you shoot yourself in the foot with this quick ref: http://www.parashift.com/c++-faq-lite/
Also grab a copy of effective c++ by scott meyers.
by 5hoom on 10/15/11, 8:14 AM
Beautifully concise!
That would normally be about a chapter per-paragraph in most C++ resources around. Well done :)
by DCoder on 10/15/11, 1:49 PM
```
  template <class ttype>
  ttype multiply(ttype a, ttype b)
  {
    return a * b;
  }
```
int * int doesn't always fit in an int. C++ Templates: The Definitive Guide suggests using a traits class to solve problems like this. Templates are a complex subject in general, and I wouldn't recommend using them without having read the aforementioned book.
by Hitchhiker on 10/15/11, 11:08 AM
I can feel a flame war and potential crusade here. Being the imps that some of us are, how can we pass up this potential opportunity for enjoyment :
http://lwn.net/Articles/249460/
p.s. best comment in defense of the original poster so far has been by Shin Lao.
p.p.s the tut was targeted for a very specific audience + purpose. It was not purporting to be Bjarne Stroustrup's next meditation. Folks can offer support to another community member _ without _ being mean.
by Hitchhiker on 10/15/11, 8:10 AM
At 29, I may not be aging. But this is beautifully clear. Like fine chocolate, coffee or poetry. Good stuff.
by tripzilch on 10/15/11, 8:54 AM
This is superb. Exactly the quick-n-dirty sort of intro to C++ I have been looking for for years, it seems.
Kudos!
by etanol on 10/15/11, 11:24 AM
«And another thing you always desired: the struct keyword is not needed in the declaration»
Someone doesn't understand the value of the "struct" keyword:
https://github.com/torvalds/linux/blob/master/Documentation/...
by Hitchhiker on 10/15/11, 8:29 AM
@ Ángel , come to think of it , you may be one of the rare souls here who may smile at this from the heart:
http://news.ycombinator.com/item?id=3114374
I second 5hoom's additional attribute that you have demonstrated.
by dbattaglia on 10/15/11, 1:18 PM
Nice quick-and-dirty guide. The only thing I personally would have added more emphasis on is explaining (via code examples) the actual use case of virtual methods: storing instances of derived objects in a base class pointer/reference, while still calling the correct runtime type's method.
by KonradKlause on 10/15/11, 9:57 AM
The author seems not to know that in C++ structs and classes are the same. The only difference betweem them is that in classes the default acccess mode is private and for structs it's public.
by LostInTheWoods2 on 10/15/11, 4:30 PM
"A quick reference for aging programmers" .. anyone else offended? Maybe someone should write a post titled "From C++ to C: A quick reference for young programmers who think they're clever"
by forgotAgain on 10/15/11, 4:56 PM
Why "aging programmers" and not just "C programmers"?
by X4 on 10/15/11, 9:25 PM
Wow.. if I were an aging C programmer I would laugh about C++, Ruby, Java programmers