Why is C king? Why not C++? The difference is just a compiler, and you can use C in C++.
Additionally, most of these people are primarily electrical engineers, and don't have as strong of a background in computer science. They've been using C for decades and it does everything they want, why would they take the time to learn the boundless complexity introduced by a language that offers them (what they perceive to be) very little?
Talking to long-time C programmers about C++ is actually surprisingly difficult: https://youtu.be/D7Sd8A6_fYU
I'm a higher level programmer. Later in my career I happen to get down to microcontrollers, what would stop me from using C++?
Your typical heap-happy usage will not go down well on a microcontroller, either. Having very constrained RAM makes heap fragmentation much more of an issue.
> Your typical heap-happy usage
Huh? 1990s C++ was typically heap-happy, which is part of the reason Java looks the way it does. Idiomatic modern C++ uses the stack as much as possible. And one can use custom allocators.
C++, when used in that way, tends to do a lot of things behind the scenes. This is perfectly okay in a place where you have an operating system and a linker that have your back. On an embedded system none of this is guaranteed.
So, C++ can be a wonderful tool in proper hands, but it is much easier to misuse than C in an embedded context.
How initialization occurred (static or otherwise) was just something we made an explicit check off item in code review.
Simply put, because you can't use the STL, or a lot of other C++ features, or only with a lot of consideration.
A whole swathe of the embedded world still cares about program size in bytes. There are some that don't, but they tend to be using Linux, and are at a higher abstraction level than many others in the industry. (Industry is kinda divided in half. Those who use tiny Linux machines, and those working with microcontrollers. It's a generalization, but generally fits.)
The stuff I work on day-to-day, usually has between 1-4kb for dynamic memory, and 8-16kb for the compiled program. That line is also usually a bit blurry, and you can move things between both at runtime, but at various costs.
With C++, you get tempted to use stuff like vector, which can blow your memory stack.
I generally work with C++, but it looks like C. I get a few things like implicit pointers, for free, but generally still have to end up making most things explicit.
But, unlike twenty years ago, I no longer have to dive into assembly unless the project is pushing it's limits. The compiler tends to be "good enough".
No. If C++ were a great language those C coders would have moved over in an instant. One of the advantages of looking at C code is that you can actually figure out in your head what the assembly will look like.
Is assembly important in microcontrollers?
Actually writing assembly is more of a last resort time.
Reading assembly is more useful, especially if your platform's debugger isn't very good.
One can do this with most C++ too. Though admittedly, non-tree virtual inheritance hierarchies, as well as member function pointers [et al] make this harder to achieve universally. I will also admit that it's easier to do with C.
If the optimizer gets its hands on either though, you may be in for a surprise no matter your choice.
In any case, C++ is copy-paste compatible with 99% of C89. So same benefits apply when using that subset.
It is plain language religion as observed at a few C++ conference talks.
The world moved from C++ to Java on the enterprise side back in the late 1990's. Why? Java was arguably faster and easier to develop in, even though many thought (including me) that C++ was technically a better language.
CppCon 2016: Dan Saks “extern c: Talking to C Programmers about C++”
https://www.youtube.com/watch?v=D7Sd8A6_fYU
Embedded Development with Dan Saks
http://cppcast.com/2016/10/dan-saks/
Regarding Java vs C++, yes the enterprise world has adopted Java, however as someone doing consulting across Java, .NET and C++, I am really seeing it coming back since ANSI C++ has picked up steam again.
I see it in projects related to IoT, AI, VR, big data,....
They are all polyglot projects with C++ plus something else, not C plus something else.
As noted, unless we are speaking about PICs with 8KB and similar, the majority of them can easily be targeted by C++, which is what Arduino and ARM mbed do.
Already in MS-DOS, on 640KB computers, using C made little sense.
When we needed performance, Assembly was the only option, because the code any compiler was generating in those days was average quality on their better days.
When performance wasn't that critical, then the improved type system, RAII, reference types, type safe encapsulations were already better than using plain C.
We even had frameworks like Turbo Vision available.
So if something like a PCW 512 didn't had issues with C++, so a modern micro-controller can also be targeted by it, except for political reasons.
Developers that are against anything other than C, even if their compiler nowadays happens to be written in C++ (e.g. gcc, clang, icc, vc).
> you can actually figure out in your head what the assembly will look like
I keep hearing this, and I don't buy it. Did you know that `gcc -O3` will turn `int add(int x, int y) { return a + b; }` into an `lea` instruction? I doubt many people do.
And it's not like the compiler will magically switch to emitting different instructions if you compile the code above as C++...
Also, C++ uses a lot more memory, which can also be a no-go when you get as little as 32kb for code+data, luckily with in-place execution.
CppCon 2016: Jason Turner “Rich Code for Tiny Computers: A Simple Commodore 64 Game in C++17”
Never cared for C beyond using it in Turbo C 2.0 for MS-DOS, and later when required to use it for university projects and client projects that explicitly required ANSI C89.
So it wasn't 64 KB, but it was perfectly usable on 640 KB systems.
The main problem has always been fighting misconceptions.
Depends on how you use it. "If you don't use it, you don't pay for it" is the C++ philosophy. If you use it as "C with objects", it should use no more memory than C with structs. If you use it as "C with polymorphism", it should use no more memory than C with function pointers.
Uh. That's a pretty obvious one.
Sometimes using address generation ports is preferable to ALU ports.
Also 'lea' can load the result in a different register from both operands, 'add' will always need to modify a register.
People have been using 'lea' for calculations since dawn of time, for example:
shl ebx, 6
lea edi, [ebx*4 + ebx + 0xa0000]
add edi, eax
This was a common way in DOS days for calculating pixel address in mode 0x13.
Really, whenever you are doing any kind of embedded or real time project you are basically doing "resource limited development". The resource can be memory, I/O, CPU or any and all of that (or more). You need to be able to control exactly how it's used. C++ is often used to abstract you away from those things -- which is exactly the opposite of what you want.
C is a high-ish level language that is close enough to the metal that you can fairly easily understand the implications of what you are doing. C++ is not and it's incredibly easy to build a monstrocity that chews memory -- not just working memory, but application size too. Even dealing with name mangling is a surprising PITA when you are dealing with embedded -- remember embedded means you often have to build your own tools because nobody else is using your platform ;-).
Like I said, I actually like C++ (or at least C++ of a couple of decades ago -- the language seems to have changed a lot since I last used it, so it's hard for me to say). There are a lot of times where I simply don't care about controlling resources to that level. These days there are a lot of other choices and I'm not sure that I would ever choose C++ for a project again, but definitely back in the day it was something I reached for quite a bit.
WRT Rust, I agree with the OP that the borrow checker is really nice. I recently spent some time playing with Rust to see how easy it was to implement higher level abstractions. One of the things I was really impressed with was how hard Rust slaps you when you try to do something that would explode your memory footprint. It still feels a bit immature to me, but it has tremendous promise (and if you don't mind working around the immaturity, it's probably fine to use at the moment).
The first obstacle was that there was no C++ compiler.
So I wrote some very C++ style C: nice little structs with associated functions for mainpulating them, which took a pointer to struct as first argument.
The code did not fit in the PIC.
It turns out that the PIC16 lacks certain indirect addressing modes, so every access to a structure member from a pointer turns into a long sequence of instructions to do the arithmetic.
Oh, and this particular chip only allows you a maximum stack depth of 8, so you have to ration your use of utility functions. The compiler is bad at inlining so macros are prefereable.
By the time I had finished it was an extremely C program with no trace of C++ style at all.
The situation has got a lot better but there are still limitations which will trip up the unwary. And one day someone's going to point out that they can save $0.50 on every one of a million devices if you use one of these tiny chips with no indirect addressing and limited stack.
As I type that, I realize I've recently learned to love Go, so maybe it is my bias.
Many embedded programmers come from a background that doesn't expose them to those sorts of ideas though.
As a software inclined embedded guy I also often think of what would be possible if we switched to C++. But then I think of what's probable.
There's a case to be made for an OO style program where I create an object and give it a chunk of memory to manage a B-tree, so I can keep my memory from being fragmented, but using C++ for that is serious overkill.
Namespaces, References, collection types (std::array, string_view, intrusive containers, etc.), RAII (release mutexes at scope ends), strong typing, proper encapsulation, interfaces, etc.
"A word of warning: Linus has very strong feelings about all the things that are wrong with C++ and at times has been known to be less diplomatic than me when explaining his point of view... :-) But he made a clear statement that he is interested in seeing this port happening, as long as most of the program logic that is not UI code stays in (quote) "sane C files". So please keep that in mind as we drive this further."
http://lists.subsurface-divelog.org/pipermail/subsurface/201...