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Thats simply not true. UB is simply the latest stick to hit C with. In day-to-day working nobody worries about UB at all as you generally don't notice it. Sam

Thats simply not true. UB is simply the latest stick to hit C with. In day-to-day working nobody worries about UB at all as you generally don't notice it. Same with lack of a GC; this is a plus point for C for most applications, not a negative. (and yes, I do have plenty of experience in it, I've been using it for the past 20 years, have you?).

catnaroek 10y ago
> UB is simply the latest stick to hit C with. Honest question, which is the case? (0) You find it easy to determine, by visual inspection, whether a piece of code has undefined behavior. (1) Your coding practices make it difficult to accidentally introduce undefined behavior in the first place. > Same with lack of a GC; this is a plus point for C for most applications, not a negative. Agreed. C addresses use cases for which GC (or any other feature requiring heavy runtime support) is simply unacceptable.
- TickleSteve 10y ago
  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.
aidenn0 10y ago
> UB is simply the latest stick to hit C with. In day-to-day working nobody worries about UB at all as you generally don't notice it. I agree that in day-to-day working nobody worries about it, and I see odd behaviors all the time because of it. In particular as fewer applications are using C, a much higher fraction of C becomes systems and embedded where you are more likely to accidentally run afoul of choices that were made to compete with FORTRAN on numerical performance. A read from NULL will crash on most unixen, but will not crash on some targets without an MPU and when running in kernel mode, so may be left lurking (see the linux kernel). The C89 aliasing rules in particular are completely at odds with a lot of kernel and device driver code, and in addition where the int size was 2 bytes previously but is now 4 bytes you can have signed overflow where before the behavior was well defined: UINT2 x; // 16 bit integer ... x+=2; // addition mod 2**16 on 16 bit targets, undefined behavior on 32 bit targets. These are some real-world bugs I've dealt with. > (and yes, I do have plenty of experience in it, I've been using it for the past 20 years, have you?). I've been using it professionally for only about 15 years, but I started using C at home in '92. [edit] > Same with lack of a GC; this is a plus point for C for most applications, not a negative. This is a bit of a non-sequitur, as I didn't mention memory management at all. C doesn't need a GC. It could use more memory safety though. There's been plenty of academic research on improving C's memory safety without significant runtime overhead; a lot of those techniques were used in rust. There are plenty of tools that can catch a large fraction of memory errors at compile time, which is a good thing.

catnaroek 10y ago

> UB is simply the latest stick to hit C with. Honest question, which is the case? (0) You find it easy to determine, by visual inspection, whether a piece of code has undefined behavior. (1) Your coding practices make it difficult to accidentally introduce undefined behavior in the first place. > Same with lack of a GC; this is a plus point for C for most applications, not a negative. Agreed. C addresses use cases for which GC (or any other feature requiring heavy runtime support) is simply unacceptable.

TickleSteve 10y ago
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.

aidenn0 10y ago

> UB is simply the latest stick to hit C with. In day-to-day working nobody worries about UB at all as you generally don't notice it. I agree that in day-to-day working nobody worries about it, and I see odd behaviors all the time because of it. In particular as fewer applications are using C, a much higher fraction of C becomes systems and embedded where you are more likely to accidentally run afoul of choices that were made to compete with FORTRAN on numerical performance. A read from NULL will crash on most unixen, but will not crash on some targets without an MPU and when running in kernel mode, so may be left lurking (see the linux kernel). The C89 aliasing rules in particular are completely at odds with a lot of kernel and device driver code, and in addition where the int size was 2 bytes previously but is now 4 bytes you can have signed overflow where before the behavior was well defined: UINT2 x; // 16 bit integer ... x+=2; // addition mod 2**16 on 16 bit targets, undefined behavior on 32 bit targets. These are some real-world bugs I've dealt with. > (and yes, I do have plenty of experience in it, I've been using it for the past 20 years, have you?). I've been using it professionally for only about 15 years, but I started using C at home in '92. [edit] > Same with lack of a GC; this is a plus point for C for most applications, not a negative. This is a bit of a non-sequitur, as I didn't mention memory management at all. C doesn't need a GC. It could use more memory safety though. There's been plenty of academic research on improving C's memory safety without significant runtime overhead; a lot of those techniques were used in rust. There are plenty of tools that can catch a large fraction of memory errors at compile time, which is a good thing.