Add C++ usage example in README.md

[generalmimon]

It's tested under Windows 10 64-bit with the g++ compiler 8.3.0. It worked, but I had to get endian.h and byteswap.h from the internet, because they're not available on Windows and the C++ runtime relies on them. Maybe the runtime should be fixed to support Windows out-of-the-box as well.

[generalmimon]

And one thing: I noticed that all usage examples for C++ (in C++ notes and format gallery) use syntax gif_t data(&ks) for instantiation, and not creating a pointer like gif_t* data = new gif_t(&ks). This works, but it implies non-intuitive syntax when it comes to reference the substructures of the generated parser. In this example, it would look like this:

gif_t g(&ks);
std::cout << "width = " << g.logical_screen()->image_width() << std::endl;
std::cout << "height = " << g.logical_screen()->image_height() << std::endl;

As you can see, when referencing data.logical_screen.image_width member, it's necessary to first use the dot . and then ->, because the generated code by KSC always uses pointers. So I opted to use them as well while instantiating the gif_t here, because the -> -> variant is much better. And I think all usage examples in the documentation and formats gallery should work this way as well.

[GreyCat]

Broadly, the idea was actually to remove this piece of quick start documentation here and have it completely in one place: https://kaitai.io/ — with interactive language switch.

On topic of C++: your current implantation leaks memory, having new without relevant delete. You either need to call that manually, or use smart pointers.

[generalmimon]

@GreyCat OK, thanks for your response, I'm closing this then. It's just that GitHub kaitai_struct repo homepage might be a possible entry point for the newcomers, and the README seems unfinished.

So the examples in this README should be deleted completely and link to the https://kaitai.io/ instead?

[GreyCat]

Yeah, I believe we wanted to do it 2-3 years ago, but never got to actually proceed.