I know C and Python, and I'm moving toward another language for learning purposes. My problem is that I like to learn things with something to do (for example contributing to some project or do something amazing, not boring plain algebra).
I would like to hear suggestions about the fields in which C++ shines and where I can find interesting programming with C++. (For fields I mean networking/GUI programming/algorithms/games ...)
I confirm that I'm interested in open source projects/development.
In the OSS world (which I am assuming you are interested in), C++ is used a lot for GUI programming in KDE project (see Qt).
But my general observation is that C++ is used more in commercial applications (games, graphics-heavy applications), whereas in open-source projects C is preferred (in combination with some high-level language wrappers like Python).
C++ is used for any field with high performance demands, as it has a valid reputation for being an extremely fast language. You'll find the very latest in technologies like DirectX and the very fastest algorithms available in C++.
Most games are written in C++ because they are relatively low-level and need access to system APIs AND they profit from object-oriented programming a lot.
I will share which fields I use the language in and why I use the language over others. Perhaps you can decide if my reasons qualify as 'shines'.
Which fields:
Device drivers, file system drivers, GUI development, algorithm modules, protocols and communications, application frameworks, data manipulation, storage handlers, system emulation.
Why:
I want to write code that is portable across a broad scale of architectures. From small 16-bit embedded systems to large enterprise platforms. This is because I dislike solving the same problems over and over again. C++ compilers are available for more platforms I target than any other OO language. I do lose this capability on very very small (i.e. 8-bit) systems but I'm not spending much time in that space anymore.
System code can be written (i.e. device drivers, FS drivers, etc.) as those require a language that compiles to native code. With careful selection of language features and libraries used it can be nearly as compact as C.
Broad usage among compiled languages so there is peer experience to draw upon as well as available libraries and source code.
Deterministic and predictable behavior over long execution runs (months to years) since the memory management scheme may be carefully selected for the application's needs.
Acceptability to my clients. They are assured that the work is maintainable since a significant pool of developers exist in the market.
I hope that helped a little.
C++ means it can do something only C can do, and something else others can do.
When you want to see its shiny side, you can call it all-around. When you assume it's an useless language, you can take the answer at the bottom :-)
In my opinion it's not much that C++ really shines, it's just I have yet to find a language that give me as much freedom.
There are drawbacks of course, the more freedom you are given the more likely you are to hang yourself (or shoot yourself in the foot, as the popular analogy goes). But after having been so free, I find it difficult to bring myself to program in another language.
C++ is, so far, the language in which I feel the less restricted, and thus the one I am the more comfortable programming with, despite its many flaws.
IMO, the single biggest strength of C++ is being able to work at almost any level of abstraction. Many languages provide (more or less) a single level of abstraction. It's generally fairly difficult to "descend" to a lower level of abstraction (at all). While you can build up higher levels of abstraction, few languages provide the facilities to let those pieces work with (or like) the rest of the language. This can lead to "pieces" that are fine and sensible individually, but still difficult to put together into a complete program that remains coherent.
Nearly the only other language I can think of right off that has roughly similar capabilities in this respect is Ada 95. In some ways, its capabilities are (theoretically) superior. Just for example, it supports more precise specifications of things like bit layouts for interfacing to hardware devices. These remain mostly theoretical though -- while C++ (like C) lacks guarantees about how the compiler will lay out things like bit fields in a struct, individual compilers give the control necessary to do the job, and code like this is rarely very portable in any case.
For a little historical perspective, read Stroustrup's Design and Evolution of C++.
Stroustrup was working on a simulation back in his grad school days, and found Simula 67 to be an excellent language for the purpose, easy to write in.
However, Simula was completely inadequate for actual use, since it was so inefficient. Stroustrup was forced to rewrite the stuff in BCPL, which was a very primitive predecessor of C, and found it extremely painful.
After that, he was determined to come up with a language that was as effective as C, but which would support Simula-style programming. The result was at first called C with Classes, then C++.
However, C++ didn't stop there. It gained other features, like templates. This allowed the Standard Template Library. Its creator, Stepanov, claimed that he'd found no other language in which he could implement it to his satisfaction. (He seemed a bit grumpy about answering the question yet again in a Lisp forum.)
C++ shines at applying advanced and potentially weird programming techniques efficiently.