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Not mentionned, about being an expert C programmer, is knowing the pitfalls of C, (cf. undefined behaviors), and reading and knowing the ANSI C standard. Of co

Not mentionned, about being an expert C programmer, is knowing the pitfalls of C, (cf. undefined behaviors), and reading and knowing the ANSI C standard. Of course, just knowing the language in and out is not enough, you also have to be a good programmer in general (algorithms, "design patterns", software architecture, software engineering, etc). But writing C code without undefined behavior, and avoiding its numerous pitfalls is absolutely necessary.

cbd1984 12y ago
If you want to become an expert C programmer, you have to know C As She Is Spoke: Compiler quirks, inclusive of bugs and non-standard enhancements, which can either trip you up or give you a lot more expressiveness, if you're tasteful about where and when you use them. For example, the GNU C typeof() operator makes certain macros a lot cleaner, but it's nowhere in the actual standard. I'm sure other compilers have similar extensions.
vadivlkumar 12y ago
operating system principles and quirks also equally important when you want a expert C programmer.
humanrebar 12y ago
> But writing C code without undefined behavior, and avoiding its numerous pitfalls is absolutely necessary. I rarely (as in unicorns) see C code that consistently checks for unsigned integer overflow. Or signed integer overflow for that matter, but that's defined behavior. Point being, I also encourage people to avoid undefined behavior, but whether and how one does that has subtleties in practice.
- FreeFull 12y ago
  Unsigned overflow is defined, signed overflow isn't.
- barrkel 12y ago
  Signed overflow is undefined, unsigned overflow is defined. But I agree with you. Not enough people take integer overflow seriously. Unsigned underflow, perfectly well defined behaviour, is actually a worse problem in practice, IMO. I think too many C programers think about unsigned types like they're a bounded type, e.g. they think "this variable can never be negative, therefore I'll give it an unsigned type". But unsigned types have a cliff of surprising behaviour right where they're commonly used - most integer values in programs are low. Whereas you really need to work on a signed value to get it to overflow.
Htsthbjig 12y ago
"Not mentionned, about being an expert C programmer, is knowing the pitfalls of C, (cf. undefined behaviors)" I am an expert in C, I had been decades writing on it and other languages, and managing teams of coders. We created a company that used it a lot. I can't understand what undefined behaviors C has, because it is the most simple and defined language I do know of. I have lots of experience writing assembler,fortran, Lisp, c++, python, objective C and also use C#, java, javascript and other web languages and functional languages from time to time. c++, java could be extremely undefined because the behavior depends on conventions, committees and implementations. E.g we had to change some code because of different compilers interpretation of the standars. But c? c is basically portable assembler. If you understand how computers work it is extremely reliable bar none. We have ported years of work of dozen programmers in one day. With c++ and "write once, run everywhere marketing" java we spent months. It was also terribly frustrating for the team. Fontforge author had a similar experience writing c++ compilers and that experience was so traumatic the interface of Fontforge is so ugly as he does not want to use c++ with a ten foot pole. We try to avoid pitfalls more in high level languages because the programmer has the ability to write code without understanding what is really happening in the processor, or even in the program. Recipe programmers population is growing a lot this days.
- mahkoh 12y ago
  >If you understand how computers work it is extremely reliable bar none. On my processor, INT64_MAX + 1 will be INT64_MIN, a negative value. But the compiler is free to turn for (int64_t i = 1; i > 0; i++) { f(i); } into an infinite loop. Understanding how the computer works without reading about undefined behavior will make you fall into these kinds of traps.
  - musername 12y ago
    missing overflow guards is just one of the big disappointments in c, if you have experience with asm for any popular processor atm.
    - MrGando 12y ago
maxlybbert 12y ago
It appears people are still writing C without appreciating the fact that "undefined behavior" means more than "unpredictable," or "might crash." A lot more: http://blog.llvm.org/2011/05/what-every-c-programmer-should-know.html http://blog.llvm.org/2011/05/what-every-c-programmer-should-... .

cbd1984 12y ago

If you want to become an expert C programmer, you have to know C As She Is Spoke: Compiler quirks, inclusive of bugs and non-standard enhancements, which can either trip you up or give you a lot more expressiveness, if you're tasteful about where and when you use them. For example, the GNU C typeof() operator makes certain macros a lot cleaner, but it's nowhere in the actual standard. I'm sure other compilers have similar extensions.

vadivlkumar 12y ago

operating system principles and quirks also equally important when you want a expert C programmer.

humanrebar 12y ago

> But writing C code without undefined behavior, and avoiding its numerous pitfalls is absolutely necessary. I rarely (as in unicorns) see C code that consistently checks for unsigned integer overflow. Or signed integer overflow for that matter, but that's defined behavior. Point being, I also encourage people to avoid undefined behavior, but whether and how one does that has subtleties in practice.

FreeFull 12y ago
Unsigned overflow is defined, signed overflow isn't.
barrkel 12y ago
Signed overflow is undefined, unsigned overflow is defined. But I agree with you. Not enough people take integer overflow seriously. Unsigned underflow, perfectly well defined behaviour, is actually a worse problem in practice, IMO. I think too many C programers think about unsigned types like they're a bounded type, e.g. they think "this variable can never be negative, therefore I'll give it an unsigned type". But unsigned types have a cliff of surprising behaviour right where they're commonly used - most integer values in programs are low. Whereas you really need to work on a signed value to get it to overflow.

Htsthbjig 12y ago

"Not mentionned, about being an expert C programmer, is knowing the pitfalls of C, (cf. undefined behaviors)" I am an expert in C, I had been decades writing on it and other languages, and managing teams of coders. We created a company that used it a lot. I can't understand what undefined behaviors C has, because it is the most simple and defined language I do know of. I have lots of experience writing assembler,fortran, Lisp, c++, python, objective C and also use C#, java, javascript and other web languages and functional languages from time to time. c++, java could be extremely undefined because the behavior depends on conventions, committees and implementations. E.g we had to change some code because of different compilers interpretation of the standars. But c? c is basically portable assembler. If you understand how computers work it is extremely reliable bar none. We have ported years of work of dozen programmers in one day. With c++ and "write once, run everywhere marketing" java we spent months. It was also terribly frustrating for the team. Fontforge author had a similar experience writing c++ compilers and that experience was so traumatic the interface of Fontforge is so ugly as he does not want to use c++ with a ten foot pole. We try to avoid pitfalls more in high level languages because the programmer has the ability to write code without understanding what is really happening in the processor, or even in the program. Recipe programmers population is growing a lot this days.

mahkoh 12y ago
>If you understand how computers work it is extremely reliable bar none. On my processor, INT64_MAX + 1 will be INT64_MIN, a negative value. But the compiler is free to turn for (int64_t i = 1; i > 0; i++) { f(i); } into an infinite loop. Understanding how the computer works without reading about undefined behavior will make you fall into these kinds of traps.
- musername 12y ago
  missing overflow guards is just one of the big disappointments in c, if you have experience with asm for any popular processor atm.
  - MrGando 12y ago

maxlybbert 12y ago

It appears people are still writing C without appreciating the fact that "undefined behavior" means more than "unpredictable," or "might crash." A lot more: http://blog.llvm.org/2011/05/what-every-c-programmer-should-know.html http://blog.llvm.org/2011/05/what-every-c-programmer-should-... .