4 ms·

Its a combination of both. The vast majority of all code you write will not invoke UB, most people tend to stick to an 'easy' subset of syntax, unlike say C++

Its a combination of both. The vast majority of all code you write will not invoke UB, most people tend to stick to an 'easy' subset of syntax, unlike say C++ where everyone uses a different subset of features making it in effect multiple languages. A combination of testing the known edge cases, wraparound issues, size issues, static analysis and tooling means running into an example of UB is extremely rare in most cases. It used to be that people used dynamic memory allocation to beat C with, but that is just a resource management issue. TBH, this is not rocket science. If you need dynamic memory allocation, you had damn well better know how to use it properly. Its an example of laziness and people ignoring the machine. Another example is performance; saying that a language comes within a factor of 2 of C's performance and therefore is fast is absolutely ridiculous. a factor of 2 is huge. You have to remember that people who write C are dealing with machine-specifics day-in, day-out. we're bit-fiddling and writing MPU code and drivers, etc. Basically, we're much more aware of the machine than higher-level softies, so what would normally be UB is actually DB in most cases, its defined by the compiler and hardware that we're intimately familiar with. ...and that isn't to say that you can't write high level abstracted code in C, the simplicity of the language lends itself to (properly) efficient implementation, not efficient in the sense of Java or Ruby ;o)

catnaroek 10y ago
> The vast majority of all code you write will not invoke UB That's a bit like saying “the vast majority of the haystack doesn't contain any needles”. > most people tend to stick to an 'easy' subset of syntax I'm not sure I understand what you mean. Undefined behavior has nothing to do with syntax. It's strictly a semantic issue. > It used to be that people used dynamic memory allocation to beat C with, but that is just a resource management issue. TBH, this is not rocket science. If I understand correctly, the objection isn't that it's rocket science, but rather that you get little help from your tools if you do it wrong. Memory debuggers will only tell you about memory management bugs that manifest themselves in a particular program run. If a bug will only manifest itself under conditions that are hard to replicate, you're out of luck. Of course, none of this is an indictment of manual memory management per se, or suggests that garbage collection is a universally good solution. But manual memory management has usability issues, which fortunately being addressed in more modern language designs like Rust. > If you need dynamic memory allocation, you had damn well better know how to use it properly. Sure, but are better compile-time diagnostics too much to ask for? Notice that compile time diagnostics don't introduce any runtime performance penalty. > Another example is performance; saying that a language comes within a factor of 2 of C's performance and therefore is fast is absolutely ridiculous. a factor of 2 is huge. No disagreement here. > so what would normally be UB is actually DB in most cases, As far as I can tell, the trend among C and C++ compiler writers is to optimize programs very aggressively under the assumption that UB simply will never happen, rather than to turn UB into DB. > its defined by the compiler and hardware that we're intimately familiar with. Well, “works on this machine” isn't good enough for most of us.
- TickleSteve 10y ago
  You're correct.... the vast majority of the haystack doesn't contain any needles, thats the point. And you also know where the needles tend to be and stay away from that area. I'm not implying that UB doesn't exist, simply saying that using C is a different mindset. If you use C, you dont just use the language, you use the language, the toolchain and the machine, you're familiar with the whole stack, quite often down to the metal. The point about memory management is that memory management is just case of the general problem, i.e. resource management. resource management is a skill you need to have if you're a softie and making it easier in one specific case (RAM) is not a generic solution. Better that you learn how to do it properly then apply that knowledge in all situations (files, RAM, power, etc). e.g. where is the GC-equivalent for power management? or file handles? its the same problem in a different domain.
  - catnaroek 10y ago
    > The point about memory management is that memory management is just case of the general problem, i.e. resource management. Wholeheartedly agree. I'm aware that GC is no solution for this problem. But I'm not arguing in favor of GC - I'm arguing in favor or making manual resource management safer, for example, like Rust does. Resource management is every single bit as manual as in C - the only difference is that the compiler yells if you do it wrong.
lmm 10y ago
> The vast majority of all code you write will not invoke UB, most people tend to stick to an 'easy' subset of syntax, unlike say C++ where everyone uses a different subset of features making it in effect multiple languages. Even integer addition very easily leads to undefined behaviour. > It used to be that people used dynamic memory allocation to beat C with, but that is just a resource management issue. TBH, this is not rocket science. If you need dynamic memory allocation, you had damn well better know how to use it properly. If you're going to solve a quadratic equation you should damn well know how to do it properly, by completing the square. But once you know that you should use the formula, because it makes it a lot easier. If you complete the square every time out of pride, you're just wasting everyone's time. > A combination of testing the known edge cases, wraparound issues, size issues, static analysis and tooling means running into an example of UB is extremely rare in most cases. Sure. You can do enough work to eliminate it. Or you can use a language where you don't need to. > Its an example of laziness and people ignoring the machine. Laziness is one of the cardinal virtues of a programmer > Another example is performance; saying that a language comes within a factor of 2 of C's performance and therefore is fast is absolutely ridiculous. a factor of 2 is huge. A factor of 2 is irrelevant most of the time. If you're growing exponentially, a factor of 2 will let you put off the point where you have to start scaling out by maybe a few months. If you're not growing exponentially, you probably won't hit performance limits at all. > Basically, we're much more aware of the machine than higher-level softies, so what would normally be UB is actually DB in most cases, its defined by the compiler and hardware that we're intimately familiar with. Until the compiler adds new optimizations. Sure, if you're never going to upgrade the compiler maybe you can get away with C. > ...and that isn't to say that you can't write high level abstracted code in C, the simplicity of the language lends itself to (properly) efficient implementation, not efficient in the sense of Java or Ruby ;o) Without native tagged unions you won't get far up the abstraction ladder. You can write your own with macros sure, but they won't interoperate with anyone else's or any libraries you'd want to use.

catnaroek 10y ago

> The vast majority of all code you write will not invoke UB That's a bit like saying “the vast majority of the haystack doesn't contain any needles”. > most people tend to stick to an 'easy' subset of syntax I'm not sure I understand what you mean. Undefined behavior has nothing to do with syntax. It's strictly a semantic issue. > It used to be that people used dynamic memory allocation to beat C with, but that is just a resource management issue. TBH, this is not rocket science. If I understand correctly, the objection isn't that it's rocket science, but rather that you get little help from your tools if you do it wrong. Memory debuggers will only tell you about memory management bugs that manifest themselves in a particular program run. If a bug will only manifest itself under conditions that are hard to replicate, you're out of luck. Of course, none of this is an indictment of manual memory management per se, or suggests that garbage collection is a universally good solution. But manual memory management has usability issues, which fortunately being addressed in more modern language designs like Rust. > If you need dynamic memory allocation, you had damn well better know how to use it properly. Sure, but are better compile-time diagnostics too much to ask for? Notice that compile time diagnostics don't introduce any runtime performance penalty. > Another example is performance; saying that a language comes within a factor of 2 of C's performance and therefore is fast is absolutely ridiculous. a factor of 2 is huge. No disagreement here. > so what would normally be UB is actually DB in most cases, As far as I can tell, the trend among C and C++ compiler writers is to optimize programs very aggressively under the assumption that UB simply will never happen, rather than to turn UB into DB. > its defined by the compiler and hardware that we're intimately familiar with. Well, “works on this machine” isn't good enough for most of us.

TickleSteve 10y ago
You're correct.... the vast majority of the haystack doesn't contain any needles, thats the point. And you also know where the needles tend to be and stay away from that area. I'm not implying that UB doesn't exist, simply saying that using C is a different mindset. If you use C, you dont just use the language, you use the language, the toolchain and the machine, you're familiar with the whole stack, quite often down to the metal. The point about memory management is that memory management is just case of the general problem, i.e. resource management. resource management is a skill you need to have if you're a softie and making it easier in one specific case (RAM) is not a generic solution. Better that you learn how to do it properly then apply that knowledge in all situations (files, RAM, power, etc). e.g. where is the GC-equivalent for power management? or file handles? its the same problem in a different domain.
- catnaroek 10y ago
  > The point about memory management is that memory management is just case of the general problem, i.e. resource management. Wholeheartedly agree. I'm aware that GC is no solution for this problem. But I'm not arguing in favor of GC - I'm arguing in favor or making manual resource management safer, for example, like Rust does. Resource management is every single bit as manual as in C - the only difference is that the compiler yells if you do it wrong.

lmm 10y ago

> The vast majority of all code you write will not invoke UB, most people tend to stick to an 'easy' subset of syntax, unlike say C++ where everyone uses a different subset of features making it in effect multiple languages. Even integer addition very easily leads to undefined behaviour. > It used to be that people used dynamic memory allocation to beat C with, but that is just a resource management issue. TBH, this is not rocket science. If you need dynamic memory allocation, you had damn well better know how to use it properly. If you're going to solve a quadratic equation you should damn well know how to do it properly, by completing the square. But once you know that you should use the formula, because it makes it a lot easier. If you complete the square every time out of pride, you're just wasting everyone's time. > A combination of testing the known edge cases, wraparound issues, size issues, static analysis and tooling means running into an example of UB is extremely rare in most cases. Sure. You can do enough work to eliminate it. Or you can use a language where you don't need to. > Its an example of laziness and people ignoring the machine. Laziness is one of the cardinal virtues of a programmer > Another example is performance; saying that a language comes within a factor of 2 of C's performance and therefore is fast is absolutely ridiculous. a factor of 2 is huge. A factor of 2 is irrelevant most of the time. If you're growing exponentially, a factor of 2 will let you put off the point where you have to start scaling out by maybe a few months. If you're not growing exponentially, you probably won't hit performance limits at all. > Basically, we're much more aware of the machine than higher-level softies, so what would normally be UB is actually DB in most cases, its defined by the compiler and hardware that we're intimately familiar with. Until the compiler adds new optimizations. Sure, if you're never going to upgrade the compiler maybe you can get away with C. > ...and that isn't to say that you can't write high level abstracted code in C, the simplicity of the language lends itself to (properly) efficient implementation, not efficient in the sense of Java or Ruby ;o) Without native tagged unions you won't get far up the abstraction ladder. You can write your own with macros sure, but they won't interoperate with anyone else's or any libraries you'd want to use.