7 ms·

Why is C king? Why not C++? The difference is just a compiler, and you can use C in C++.

by pknopf 9y ago

dingo_bat 9y ago
I don't know why. But it's true.
bb88 9y ago
Here's a rant by Linus Torvalds. Take the politics and snark with a grain of salt. His technical arguments, however, are spot on. http://harmful.cat-v.org/software/c++/linus http://harmful.cat-v.org/software/c++/linus
- Inityx 9y ago
  I'm not sure how much water his argument here holds anymore. C++ has changed A LOT since 2007; idiomatic C++11 is an extremely different language from C++03, and C++20 is almost unrecognizable to an early C++ developer.
  - bb88 9y ago
    I bet you $5 if you ask him, he'd probably say the exact same thing.
    - scottlamb 9y ago
      He writes C++ now, so I imagine he'd say the language has its place. https://en.wikipedia.org/wiki/Subsurface_(software) https://en.wikipedia.org/wiki/Subsurface_(software) (He'd probably still say C++ is inappropriate for the Linux kernel, though.)
      - bb88 9y ago
        I was going to honor my bet here, until I did a little googling and found this during the discussion of when they ported subsurface to Qt. "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/2013-March/005365.html http://lists.subsurface-divelog.org/pipermail/subsurface/201...
Analemma_ 9y ago
I’m not an embedded developer, but my guess is that if they’re not even using dynamic memory, I doubt they need or want anything that C++ has to offer.
- pknopf 9y ago
  I can see people arguing for object oriented over procedural. As I type that, I realize I've recently learned to love Go, so maybe it is my bias.
- tarmon 9y ago
  There is still a lot to be gained by strong typing even in projects where everything is statically allocated.
- jwhite 9y ago
  That's more a matter of experience and attitude -- even simple things like reference types are nice. Also, templates offer a lot of abstraction power that can be used to model the hardware nicely, without sacrificing efficiency. Many embedded programmers come from a background that doesn't expose them to those sorts of ideas though.
  - carlmr 9y ago
    Can confirm, C++ has some nice features which I'd even like without malloc. OTOH I'm already horrified at the code quality problems pretty much every embedded shop faces. C++ would only make this matter worse. 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.
- bb88 9y ago
  Many people need in memory databases and linked lists (or binary trees) to hash information and sort it. 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.
- 9y ago
Inityx 9y ago
C is king because the industry is currently dominated by people who have been doing this since before C++ was a thing. 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 https://youtu.be/D7Sd8A6_fYU
- pknopf 9y ago
  Let me ask it this way: I'm a higher level programmer. Later in my career I happen to get down to microcontrollers, what would stop me from using C++?
  - jwhite 9y ago
    Nothing. I've worked on Cortex-M4 projects in C++. It's nice in many ways. The people working on the project had a much more diverse background than the typical EE who learned C as an undergrad mentioned in another thread.
  - q3k 9y ago
    The standard library (with all its' duplicate code resulting from hardcore templating) will blow up your flash space usage significantly, to the point where you will run out of it sooner than you expect. You will spend time finding alternative standard libraries that are size-optimized and you might end up rewriting a lot of what you take for granted in your C++ daily usage. For example, the Arduino environment is C++-based, but it's not anything like on the desktop due to it not shipping an std:: . 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.
    - atilaneves 9y ago
      Then don't use the standard library. Don't even link it in. > 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.
mikekchar 9y ago
It's more difficult. I used C++ in many projects for years and enjoyed working with it. You have to be very disciplined, though, and you need to know a lot about how it works under the hood to get it to play nicely, but it has it's niche. Embedded is not it's niche IMHO (and I've also done embedded, where we specifically chose to use C over C++). 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).
tluyben2 9y ago
I find it easier to use C and assembly on very constrained devices becauee I know what the output will be; with C++ it is less clear. If you write code that has to fit in 24kb, you need to think about what every instruction looks like after compilation and that just is far easier with C and (obviously) asm in my experience.
pjc50 9y ago
About 15 years ago I did some PIC16 programming immediately after a lot of C++, so I tried working in a C++ style. 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.
s73v3r_ 9y ago
A lot of it is due to the fact that many of these chips use ancient compilers, so the C++ support isn't that good.

Why is C king? Why not C++? The difference is just a compiler, and you can use C in C++.

by pknopf 9y ago

Why is C king? Why not C++? The difference is just a compiler, and you can use C in C++.

dingo_bat 9y ago

I don't know why. But it's true.

bb88 9y ago

Here's a rant by Linus Torvalds. Take the politics and snark with a grain of salt. His technical arguments, however, are spot on. http://harmful.cat-v.org/software/c++/linus http://harmful.cat-v.org/software/c++/linus

Inityx 9y ago
I'm not sure how much water his argument here holds anymore. C++ has changed A LOT since 2007; idiomatic C++11 is an extremely different language from C++03, and C++20 is almost unrecognizable to an early C++ developer.
- bb88 9y ago
  I bet you $5 if you ask him, he'd probably say the exact same thing.
  - scottlamb 9y ago
    He writes C++ now, so I imagine he'd say the language has its place. https://en.wikipedia.org/wiki/Subsurface_(software) https://en.wikipedia.org/wiki/Subsurface_(software) (He'd probably still say C++ is inappropriate for the Linux kernel, though.)
    - bb88 9y ago
      I was going to honor my bet here, until I did a little googling and found this during the discussion of when they ported subsurface to Qt. "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/2013-March/005365.html http://lists.subsurface-divelog.org/pipermail/subsurface/201...

Analemma_ 9y ago

I’m not an embedded developer, but my guess is that if they’re not even using dynamic memory, I doubt they need or want anything that C++ has to offer.

pknopf 9y ago
I can see people arguing for object oriented over procedural. As I type that, I realize I've recently learned to love Go, so maybe it is my bias.
tarmon 9y ago
There is still a lot to be gained by strong typing even in projects where everything is statically allocated.
jwhite 9y ago
That's more a matter of experience and attitude -- even simple things like reference types are nice. Also, templates offer a lot of abstraction power that can be used to model the hardware nicely, without sacrificing efficiency. Many embedded programmers come from a background that doesn't expose them to those sorts of ideas though.
- carlmr 9y ago
  Can confirm, C++ has some nice features which I'd even like without malloc. OTOH I'm already horrified at the code quality problems pretty much every embedded shop faces. C++ would only make this matter worse. 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.
bb88 9y ago
Many people need in memory databases and linked lists (or binary trees) to hash information and sort it. 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.
9y ago

Inityx 9y ago

C is king because the industry is currently dominated by people who have been doing this since before C++ was a thing. 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 https://youtu.be/D7Sd8A6_fYU

pknopf 9y ago
Let me ask it this way: I'm a higher level programmer. Later in my career I happen to get down to microcontrollers, what would stop me from using C++?
- jwhite 9y ago
  Nothing. I've worked on Cortex-M4 projects in C++. It's nice in many ways. The people working on the project had a much more diverse background than the typical EE who learned C as an undergrad mentioned in another thread.
- q3k 9y ago
  The standard library (with all its' duplicate code resulting from hardcore templating) will blow up your flash space usage significantly, to the point where you will run out of it sooner than you expect. You will spend time finding alternative standard libraries that are size-optimized and you might end up rewriting a lot of what you take for granted in your C++ daily usage. For example, the Arduino environment is C++-based, but it's not anything like on the desktop due to it not shipping an std:: . 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.
  - atilaneves 9y ago
    Then don't use the standard library. Don't even link it in. > 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.

mikekchar 9y ago

It's more difficult. I used C++ in many projects for years and enjoyed working with it. You have to be very disciplined, though, and you need to know a lot about how it works under the hood to get it to play nicely, but it has it's niche. Embedded is not it's niche IMHO (and I've also done embedded, where we specifically chose to use C over C++). 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).

tluyben2 9y ago

I find it easier to use C and assembly on very constrained devices becauee I know what the output will be; with C++ it is less clear. If you write code that has to fit in 24kb, you need to think about what every instruction looks like after compilation and that just is far easier with C and (obviously) asm in my experience.

pjc50 9y ago

About 15 years ago I did some PIC16 programming immediately after a lot of C++, so I tried working in a C++ style. 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.

s73v3r_ 9y ago

A lot of it is due to the fact that many of these chips use ancient compilers, so the C++ support isn't that good.