3 ms·
> Undefined behavior UB in C has some unfortunate historic problems, and is _probably_ way too complicated. But UB per se is needed for a number of really impo
by jstimpfle 6y ago
> Undefined behavior
UB in C has some unfortunate historic problems, and is _probably_ way too complicated. But UB per se is needed for a number of really important optimizations - for example, for array indexing using 32-bit integers you need to be able to assume that index-scaling operations (implemented as multiplications/shifts) don't overflow.
> null terminated strings
null terminated strings are like 10-50% space savers compared to string + length tuples for realistic strings (which are small). They're also easy to pass around and require no bikeshedding what's the best string type.
You can easily make your own type if you want (struct String { const char *buffer; int length; }) or you can just use C++ and one of the more terrible full featured string types with all sorts of badly matching built-in memory management and what not.
(By the way, the issue with SetLength() that I described in my other comment applies to Pascal Strings, too)
(Oh, and Pascal/Delphi also wants you to choose between PChar, String, AnsiString, WideString and what not, and for every little thing you're doing you need to locate and use the proper API for whatever string type you've chosen. Or you need to do conversions before the calls, with all the necessary implicit memory allocations. Enjoy!)
(Oh, this is basically how I achieved a 100x-1000x speedup in a module of a business application in a short Delphi stint. I converted the string data to chunk-allocated bytes with manually computed indexing - instead of allocating thousands of little strings and throwing them back and forth. That reduced the total application startup time (including a lot of code that I never touched) from minutes (in some cases) to something bearable (1-5 secs).
> with the attendant buffer overflows are not fundamental constants of low level programming
Of course they are. If you're not controlling bytes directly, and deciding about data layout and tradeoffs, I wouldn't call that low-level programming. YMMV. But - while my code is never fuzzed - it's been years since I've been bitten by a string bug. The importance of this stuff is way overblown, and knowledge and experience how to program with simple data structures is only found in more obscure corners of the internet. Also, very little in systems programming is about strings.
- wffurr 6y agoOptimization war stories aside (which is cool, thank you!), this reads like the classic apologetics "C is fine if you just use it correctly". Whereas in practice large C and C++ projects and libraries regularly suffer from severe security vulnerabilities exploited in the wild specifically from buffer overflows and use-after-free bugs.
- jstimpfle 6y agoThere is also "Rust is fine once you know how to not get burnt by the type system, and if you carefully choose your dependencies it will maybe still be able to start a build of your project a month from now, and if you're lucky it will build in less than a lifetime". Or "Java is fine if your fingers aren't sore yet and if you don't mind the latency spikes for your interactive application or if you're basically programming like C with training wheels and less performance". ;-)
- earwaxauditor 6y agoAt least “this code doesn’t compile” isn’t a potential security vulnerability.
- jstimpfle 6y agoSure, and projects that never ship aren't either.
- earwaxauditor 6y agoI think you should lighten up ;)
- wffurr 6y agoThat's exactly the point I was trying to make.
- kaba0 6y agoAs for the latter: Or you know, most applications don’t need manual memory management because more often than not, programmers WILL get it wrong. Unless you really need that level of control over the hardware, you ARE better off with a good runtime env
- jstimpfle 6y agoThat may be, but personally I am interested in those applications - GUI work, signal processing, low-latency networking.