As a Java developer, C or C++?

Question

I've been writing Java professionally for the last 5 years. Recently, I've had to dig into JNI a bit to call some Windows specific functions.

This experience has highlighted my poor command of the C (or C++ for that matter) language. My only introduction to C was a brief "dummies" book that I read in high school 11 years ago.

I know that both languages have advanced in that time frame, especially C++ and the standard library.

Would it be appropriate for me to learn C or C++? Which books would be best?

Do folks also have any recommendations for Windows programming as well? I can read through MSDN well enough to figure out certain API calls but I have a feeling I'm missing things in regards to the "big picture".

Thanks

Answer 1

I think that C++ would be much easier for you to become proficient in than C.

If you've been using Java, you'd have a hard time doing away with conveniences like classes, exceptions, a form of references, dynamic binding, etc. and of course, decent libraries.

However, you should learn C first to make sure you really understand what's under the hood and get to experience pointers and their use and the feeling of working "with no protective gear".

Once you master that, learn about the inheritance mechanisms in C++ and how it's different from Java (e.g., multiple inheritance).

Answer 2

This really depends on your strengths and weaknesses. If you really like design patterns, then I'd suggest using C++, but if you just have to implement a couple simple methods in JNI, then I would recommend C. Learning C before C++ should give you a better understanding of memory management without having to worry about some of the complexities of C++ (constructor call order, destructors, and other differences between c++ and java).

I would suggest "The C Programming Language" by Richie and Kernighan as the definitive manual for learning C. http://www.amazon.com/Programming-Language-Dennis-M-Richie/dp/0876925964

If you're on a *nix system, there's ample documentation in the manpages for different functions. For example,

bash$ man malloc

Answer 3

If you have a good understanding of Java, I'd recommend that start with C, if you start directly with C++ there're a lot of differences between it and Java, and you probably will dislike it.

If you are serious about learning both languages I'd recommend "The C++ Programming Language" by Bjarne Stroustrup, and "The C Programming Language" by Dennis Ritchie.

Answer 4

I guess it depends on your objectives.

If you want to get closer to the machine, then C.

If you want to supplement you knowledge of a OO Java-like layer above C, then C++.

Accelerated C++ (sanitised Amazon link) is an awesome book to learn C++ from the point of view of C++ and not just C with other bits tacked on,

And K'n'R C (sanitised Amazon link) is still the way to go for learning C IMHO!

BTW For C++ follow up with the wisdom of Scott Meyers in the Effective C++ books! And his Effective STL book as well.

HTH

cheers,

Rob

Answer 5

Good question. On the surface, it'd be obvious to recommend C++, because "it's object oriented like Java". Only problem is, it's not really true.. C++ allows OOP, yes, but it's just one of several paradigms that C++ supports. Treating C++ like a OOP language (and especially, treating it like Java) will only lead to frustration.

The problem is that Java and C++ don't actually have much in common. Java programmers often believe that Java was inspired by C++, but that's only true if by C++ you mean the very earliest versions of C++, which might more appropriately be called "C with classes". Since then, C++ has transformed completely into its own language with its own way of doing things. It has probably changed far more since then than Java has. A Java programmer back then would still be able to make sense of today's Java code. Not so for C++. So I'd argue that C is actually closer to Java than "modern C++" is. C is what you get if you take Java and strip away the GC and the concept of classes and a few other abstractions. To arrive at C++, you have to add a similar number of features to our hypothetical stripped-down Java as well.

Further, C++ is a remarkably complicated language, and learning it well takes ages. And if you don't learn it well, you're going to shoot yourself in the foot over and over again.

Finally, it depends on your objectives. C++ is a much more modern language than C, and once you learn it, very expressive and powerful and, surprisingly, it can even be very elegant and concise. But the learning curve is nasty. So for native programming in the long term, I'd recommend C++ over C.

But if your goal is primarily to interface with the Win32 API (or other native API's for that matter), you won't need C++. Win32 and most other API's are written in C, not C++, and you most likely won't need very complex code to interface between that and Java in any case.

About learning Win32, you're right, all the details you need are on MSDN. If you want the big picture, Petzold is the book on the subject.

Answer 6

Learn C++.

You will find it very similar to Java with the exception of garbage collection. Additionally, C++ is generally a super set of C, so to some extent by learning C++ you will also be learning C. The converse is not true.

Answer 7

Learn enough C++ to use it as "a better C". You don't have to try to map all of it onto your understanding of Java. All you want is to be able to use C++ objects as abstract data types, new and delete, etc. If STL comes along for the ride, so much the better.

The real question is: Why do you think that JNI is such an absolute necessity? The Windows calls will ruin any thought of keeping your app portable. I'm sitting next to a guy who's having to dig into a Java app that uses JNI. It randomly brings down a server with a SEG FAULT. His hypothesis is that the heap fills up, a JNI call is made to a routine that calls malloc to allocate space on the heap. It's not available, the routine doesn't check the returned pointer for null, deallocates it, and down comes the server. He's still trying to reproduce the error locally, because it requires precise timing to call the JJNI method just before the GC starts up.

100% sure they're required? Just asking....

Answer 8

If your intent is to continue writing JNI code then I'd definitely recommend C++.

In particular, the JNI interface requires you to acquire (and subsequently release) references to Java objects. Using C++ auto variables you can get these references using 'RAII' (Resource Allocation is Initialisation) techniques which makes memory management far simpler.

Answer 9

100% sure they're required? Just asking....

Unfortunately, yes.

Thanks everyone for your answers.

To answer some of the follow up questions, I'm not looking for a career change to C or C++. I'd just like to learn the fundamentals so I don't feel like I'm flying blind when I do need to write bits and pieces.

Answer 10

In particular, the JNI interface requires you to acquire (and subsequently release) references to Java objects. Using C++ auto variables you can get these references using 'RAII' (Resource Allocation is Initialisation) techniques which makes memory management far simpler.

Thanks, that is helpful. One of the areas that stoked the growing concern in my stomach was dealing with manually managing the memory associated with the JNI objects

Answer 11

If you want an excellent resource for C, "The C Programming Language" by Dennis Ritchie is the book to get.

Answer 12

If your "main goal" here is to do windows programming, I'd recommend C# over C or C++. However I believe every programmer on Earth, and in Lower orbit, SHOULD know C. Not knowing C++ is acceptable, although you might not get invited to a few parties :) But C is something of a rite of passage, between Applications (high-level) programmer and Library (low-level) programmer.