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What’s New in C in 2023?
- fowl2 3y ago[70 minute video]
- naruhodo 3y ago[no written transcript] also [no way to adjust playback speed]. TL;DW auto, constexpr from C++ and I made a mental note to find a better source.
- Jtsummers 3y agoOn desktop (so maybe not on mobile?) there are three vertical dots. Click on that and there's an option to select playback speed.
- _trackno5 3y agoSounds like C and C++ are converging? Wikipedia has a good summary of the changes https://en.wikipedia.org/wiki/C23_(C_standard_revision) https://en.wikipedia.org/wiki/C23_(C_standard_revision)
- arp242 3y agoMost of the stuff it imported from C++ are relatively minor convenience things, not radical paradigm shifts. You make it sound like C23 started adding stuff like classes or templates.
- flohofwoe 3y agoThe video actually makes it an important point that this is not the case since C and C++ are different languages with different design philosophies. However, in the areas where they overlap, it makes sense to eliminate silly differences (like 'func()' vs 'func(void)' or '= {};' vs '= {0};'). Auto and constexpr fix specific problems that also exist in C (auto is useful in type-agnostic macros, and constexpr finally fixes the problem that a const isn't actually a constant. One interesting tidbit (which I didn't know yet) is that the C committee requires two real-world implementations for a proposal to even be considered (with the C++ standard counting as "implementation"), while the C++ committee doesn't require an implementation. Meaning C++ users are essentially guinea pigs for the C standard ;) Explains why C++ has become such a hot mess, while C has been mostly spared any serious f*ckups (I can only think of one: VLAs, but those have essentially been removed from the standard in C11).
- uecker 3y agoVLA were not removed. VLAs are almost always better than the next best alternative: - They are better than alloca due to proper scoping and standard compliance. - They use less stack than regular arrays on the stack with a worst-case size (e.g. a divide-and-conquer algorithm that may need O(N^2) stack space without VLAs could potentially be written using O(N log(N))) - VLAs can allow more accurate bounds checking than with worst-case sized arrays. - VLAs are faster than heap allocation. There are issues with VLAs: If the size is controlled by an attacker, then this could cause security issues. This is largely mitigated by -fstack-clash-protection which transforms this into a DOS (same as unbounded heap allocation) and you want to have stack clash protection anyway. Static analysis tools and compiler flags can also help to detect cases where the size is controlled by input from the network. Assembler for VLAs worse than for fixed size array, but this goes at the cost of less space saving. But, again, people who avoid VLAs blindly because of these issues then often use something which is worse. Also note that most other languages except C++ also have VLAs.
- arp242 3y agoHas anyone ever encountered trigraphs in the wild? (in real code, IOCCC doesn't count) I've seen K&R C a few times, even in modern (well, "modern") code, but I don't think I've ever encountered trigraphs. The proposal mentions that "instances of trigraphs being deliberately used in production code" via a codesearch.com query, but that's public code only (and probably only recent, and incomplete?) [1]: https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2940.pdf https://www.open-std.org/jtc1/sc22/wg14/www/docs/n2940.pdf
- AlotOfReading 3y agoNever seen intentional trigraphs in the wild and I doubt most people have given that they're disabled by default in GCC. A search did turn up whatever the fuck this is though: https://searchcode.com/file/12650181/blib/lib/prawda/grammar/english_russian/sub.h/ https://searchcode.com/file/12650181/blib/lib/prawda/grammar... Doesn't turn into anything meaningful with trigraph replacement. I'd guess that it's essentially a giant regex matching a header in some horrible, unknown dialect, but I'm not brave enough to look through the codebase to find out.
- yakubin 3y ago> they're disabled by default in GCC They’re disabled for gnuXX values of the -std= flag, but enabled for cXX. And for the latter you can’t disable them by any finer-grained flag.
- AlotOfReading 3y agoThe Gnu dialect is assumed if you don't specify arguments, hence default.
- arp242 3y agoThat file got mangled moving across encodings; the original[1] is in KOI8. https://imgur.com/a/xLUw0p8 https://imgur.com/a/xLUw0p8 [1]: https://code.google.com/archive/p/pravda https://code.google.com/archive/p/pravda
- 3y ago
- unwind 3y agoObviously there is also a summary in Wikipedia [1] which might be quicker to access (caveat: I didn't watch the video). [1]: https://en.wikipedia.org/wiki/C23_(C_standard_revision) https://en.wikipedia.org/wiki/C23_(C_standard_revision)
- c0balt 3y agoFinally, no more `#define true 1`.
- Alifatisk 3y agoYou can just include stdbool.h Works since C99
- Gibbon1 3y agoAlways irked me they created an include for just that instead of sticking it in stdint.h
- DerekL 3y agoProbably because some code already defines “bool”, “true”, and “false”, so adding those to an existing header would break it.
- c0balt 3y agoI know, in my university tasks however we were not allowed to include additional files, like stdbool.h. it has become a habit afterwards.
- ahoka 3y agoI am out of the loop, but still no strlcpy equivalent? Is it still “just use snprintf”?
- Joker_vD 3y agoJust use memccpy. Or just don't use NUL-terminated strings, seriously: zero-terminated arrays are very uncommon except when it comes to char arrays in which case they're everywhere.
- ChrisRR 3y agoIf only embedded compilers would support anything past C99. Hell, Microchip's version of GCC only got C99 support in Nov 2021
- demondemidi 3y agoEmbedded will switch to Rust before c23. I’m not joking. I’m not a rust user but every semi vendor is talking.
- Zambyte 3y agoI used Kagi to generate a summary of the video and generate a list of key moments: The podcast discusses recent and upcoming changes to the C programming language in versions C23 and beyond. It explores new features being adopted from C++, such as auto type inference, attributes, and variably modified types. These changes aim to improve compatibility while staying true to C. The presentation highlights the addition of bit-precise integer types that allow specifying exact bit widths and avoid integer promotions. It also covers new Annex F functions for improved support of IEEE 754 floating point operations. Overall, the podcast examines exciting updates to C that enhance functionality, performance, and security for developers. - C has seen significant changes over the past 12+ years for the first time, with C23 introducing many new features. - Some of the new features in C23 are inspired by C++, such as attributes and auto type inference, but aim to stay true to C's spirit. - Attributes allow providing additional information to the compiler without changing code behavior, and can be standard or vendor-specific. - Auto type inference makes generic macros easier to write by inferring parameter types. - Enumerations can now specify their underlying type, like long or unsigned int, for more control over sizes. - Variably modified types allow array sizes to depend on non-type parameters without stack allocation issues. - New integer types like intN_t specify exact bit widths and avoid integer promotions. - New macros help with endianness and bit manipulation operations in a portable way. - Annex F for floating point is now in parity with IEEE 754-2008 for more consistent floating point behavior. - Memory clearing functions like memset_s were added to improve security by overwriting secrets before freeing memory
- irundebian 3y agothank you
- demondemidi 3y ago%b and ‘ tiny but helpful
- simonblack 3y agorndm says: 2023-10-02 at 6:54 am Can we just go back to C99? Give that man $100.
- krueger71 3y agoWhat's the opinion here on decimal floating point (_Decimal32/64/128)? I'm guessing there's a significant amount of business software using double for monetary amounts out there that could benefit this being standardized. I think it has been in gcc for over a decade as an extension though...
- sigsev_251 3y agoThe extension was the reference implementation of the TS. As for its uses, IBM was the main organisation to push for this (they implemented DFP extension on gcc too) so I guess their customers (most probably on the mainframe business) have a need for it.
- deleted 3y ago[deleted]
- ngcc_hk 3y agoC99 to C23 is not obvious to … Not in our lifetime I know, but we sort of understand why we have year 2000 problem. It seems as human, we know what that missing years are or “reverse numbering” is ok.
- cozzyd 3y agoAs long as the C committee avoids publishing standards in 2089, 2099, 2111, 2114, 2117 and 2123, the numbering scheme can go on for at least another 100 years...
- demondemidi 3y agoI still don’t understand _Generic. But I’m glad to see 0x66’53’ef’03 and printf(“%b”,x); and bsearch and all the bit functions.