[kaba0]

What exactly is a problem with C++’s strings, or especially Rust’s? Everything you mentioned can be controlled as explicitly as you want.

The only problem is C is simply not expressive enough to have proper abstractions like that.

[flohofwoe]

I don't even know where to start with C++ stdlib string problems, but being mutable and doing a unique heap allocation (above a certain length - a behaviour which however isn't even standardized) are definitely at the top of the list.

std::string_view would have been a good thing if it hadn't added another memory corruption foot gun.

A universal string type is one of those things where you can either have convenience or performance, but never both.

[pjmlp]

They are still better than str...() and mem...() all over the place, and all relevant C++ compilers have options to turn bounds checking on.

[scoutt]

Last time I checked "Formatting is Unreasonably Expensive for Embedded Rust" (1)

And/or you need a crate like alloc, heapless, etc.

For the sake of a sprintf "abstraction"...

(1) https://jamesmunns.com/blog/fmt-unreasonably-expensive/

[orf]

It’s not really a sprintf abstraction.

[kjs3]

If all you do is write code on Linux/Windows/MacOS, C++ strings might be fine. Things are different in the wider world. Many places I use C don't even have a C++ compiler (embedded, in particular).

[coldtea]

>What exactly is a problem with C++’s strings, or especially Rust’s? Everything you mentioned can be controlled as explicitly as you want.

Everything else, however, cannot.

[kaba0]

Like what? C++ and Rust can do everything C can.

[tourmalinetaco]

They literally cannot. For one, neither C++ or Rust conform to standard C, meaning they already deviate from what C does on a basic level.

Their industry uses are highly different as well. C is almost a requirement for embedded systems, and while C++/Rust can be used there, they’re simply too complex and in Rust’s case additionally too young to be adopted. C++, and possibly Rust (if it can get its act together), are more used in high level programming, as that’s what they’re built for.

If C++ could do what C can, then why is the Linux kernel 98.5% C code? Wouldn’t it be better to use a more varied and powerful language?

Or, maybe different languages have different use cases and cannot be directly slotted in to replace one another.

[kaba0]

So your answer is “because they are not C”…?

What does language complexity has to do with anything? It will get compiled down to machine code, and both can be and are used for embedded. They occupy the exact same low-level niche as C, hell, they may be even more level as they can also do things like SIMD.

Linux kernel is C because Linus doesn’t like C++, it’s that easy. And usually no, why would you use multiple languages in a project if you don’t have a good reason?

[cozzyd]

It is quite difficult to write idiomatic C++ without memory allocation, for one, which is often a requirement for embedded code or any high-availability code that is not allowed to have memory fragmentation.

Sure, it's possible (you can write C in C++, for the most part, and to its credit, C++ has placement new). But many of C++'s niceties require memory allocation, making much of its value-add over C questionable.

[pjmlp]

It super easy, we did it all the time back in the MS-DOS days.

[tialaramex]

Linux isn't written in standard C. Not only does it not accept C's aliasing rules (hence the kernel is compiled with them disabled, which the standard doesn't offer), it doesn't even accept the memory model, because it had its own memory model first and it likes that one better.

As a result to some extent GCC and Clang are also compilers for some sort of "Linux C" which is strongly reminiscent of the ISO standard language but distinct.

And there's no reason you would choose C++ for a project where you'd otherwise use C on account of the (exaggerated) relationship between the two languages, the reason you'd do it would be that you want C++ features, and Linus doesn't want C++ features. Projects to "just" compile the existing Linux code but with C++ compilers failed AFAIK.

[shrimp_emoji]

I'll just leave this here: https://lkml.org/lkml/2018/6/5/769 ;p

And maybe this: https://dl.acm.org/doi/10.1145/3477113.3487274

[flohofwoe]

Unions for type punning is actually entirely valid in C, it's only UB in C++.

(I agree though that the C standard isn't actually relevant in the real world, most C compilers treat it more or less as a 'suggestion', unless enforced with options like '-pedantic')