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Git's list of banned C functions

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Re: Git's list of banned C functions

#441

Post by de6u99er »

InvOfSmallC wrote: post #103
jchw wrote: post #45

Earlier quoted context omitted.

Unfortunately, much of the pain with C surrounds dealing with strings. It’s been a bit of a theme on Hacker News for the past few days, but it’s actually a pretty good spotlight on something I feel is not always appreciated - strings in C are actually hard, and even the most safe standard functions like strlcpy and strlcat are still only good if truncation is a safe option in a given circumstance (it isn’t always.) (…

I teach at university as external lecturer. Teaching strings in C is the hardest thing I have to do every time. The university decided to explain C to first year student without previous experience. My feedback was to do a precourse in Python to let them relax a bit with programming as a concept and then teach C in a second course.

I am seeing Python becoming the go-to language for many academics because it's easy to hack something together that somehow works.

Unfortunately most of those developers don't care much about efficiency and Python is out of the box inefficient compared to other high-level languages like Java [1] or C#. OO Java courses circulating in academia lack modern functional, and to be frank educational, concepts and must to be refreshed first.

I personally would recommend to start with Java and Maven because it's still faster than C# [2], open source, and has a proven track record in regards of stability and backwards compatibility. Plus quickly introduce Spring Framework and Lombok to reduce boiler plate code.

For advanced systems programming I suggest looking into Rust instead of C/C++.

And last but not least the use of IDE's should be encouraged and properly introduced, so aspiring developers are not overwhelmed by them and learn how to use them properly (e.g. refactoring, linting, dead code detection, ...). I recommend Eclipse with Darkest Theme DevStyle Plugin [3] for a modern look.

[1] https://benchmarksgame-team.pages.debian.net/benchmarksgame/...

[2] https://benchmarksgame-team.pages.debian.net/benchmarksgame/...

[3] https://marketplace.eclipse.org/content/darkest-dark-theme-d...

Re: Git's list of banned C functions

#442

Post by edoceo »

orwin wrote: post #184
InvOfSmallC wrote: post #103

Earlier quoted context omitted.

I teach at university as external lecturer. Teaching strings in C is the hardest thing I have to do every time. The university decided to explain C to first year student without previous experience. My feedback was to do a precourse in Python to let them relax a bit with programming as a concept and then teach C in a second course.

In my school, we had two days to understand the basics of text editors, git (add, commit, rebase, reset, push) and basic bash functions (ls, cd, cp, mv, diff and patch, find, grep...) + pipes, then a day to understand how while, if/else and function calls work, then a day to understand how pointer work, then a day to understand how malloc(), free() and string works (we had to remake strlen, strcpy, and protect them).…

F. This sounds too hard. I mean, I know how to turn code into money but I'd fail this.

Re: Git's list of banned C functions

#443

Post by CodeArtisan »

throw0101a wrote: post #428
retrac wrote: post #166

Earlier quoted context omitted.

For reasons that were never clearly articulated, the prefix approach was considered odd, backwards, and to have numerous downsides, at least where I learned C. In hindsight, I can only cringe at that attitude. Strings as added in later Pascal, about 40 years ago now, were memory safe in a way that C strings still are not.

(Many of) The trade-offs were known to Richie et al ; writing in 1993: > None of BCPL, B, or C supports character data strongly in the language; each treats strings much like vectors of integers and supplements general rules by a few conventions. In both BCPL and B a string literal denotes the address of a static area initialized with the characters of the string, packed into cells. In BCPL, the first packed byte con…

We could say that a string in C is an implicit type like a list in Lisp.

Re: Git's list of banned C functions

#444

Post by mjcohen »

WalterBright wrote: post #435
jchw wrote: post #45

Earlier quoted context omitted.

Unfortunately, much of the pain with C surrounds dealing with strings. It’s been a bit of a theme on Hacker News for the past few days, but it’s actually a pretty good spotlight on something I feel is not always appreciated - strings in C are actually hard, and even the most safe standard functions like strlcpy and strlcat are still only good if truncation is a safe option in a given circumstance (it isn’t always.) (…

Whenever I review C code, I first look at the string function uses. Almost always I'll find a bug. It's usually an off by one error dealing with the terminating 0. It's also always a tangled bit of code, and slow due to repeatedly running strlen. But strings in BASIC are so simple. They just work. I decided when designing D that it wouldn't be good unless string handling was as easy as in BASIC.

IIRC, in the early days of the Commodore PET, it used a method of keeping track of strings that was fine in an 8k machine but was too slow in a 32k machine. They had to make a change that avoided quadratic time on the larger machine. So string handling in BASIC wasn't always that simple.

Re: Git's list of banned C functions

#445

Post by blahedo »

kab_al_ashraf wrote: post #423
hguant wrote: post #312

Earlier quoted context omitted.

Python is great fun, and you can be really productive with it, but for people first coming into programming, a language with an explicit and strict type system is invaluable. I used to think that everyone should be taught python first, because it lets you focus on the meat of computer science - algorithms, data manipulation, actually _doing_ something - but after helping my girlfriend out with some comp sci 101-104 p…

> You can work yourself into some weird corners because of how permissive the language is, where in a (strongly) typed language, the complier just says no. Could you share an example?

Here's one my (intro programming, non-major) students have just been tripping over this week:

  if word == "this" or "that":
      ...
Not an error, always runs. Very mysterious to a beginner. (Shared with C/C++) Another one:

  counter = "0"
  for thing in things:
      if matches(thing):
          counter += 1
The error is in the init, by someone who is overzealous with their quoting, but the error is reported, as a runtime error, on the attempted increment, which throws a TypeError and helpfully tells them "must be str, not int", and of course I know exactly why it's reporting the problem there and why it's giving that error, but it's a bit confusing to the newbie programmer and it doesn't even turn up until they actually test their code effectively, which they are also still just learning how to do.

Re: Git's list of banned C functions

#446

Post by Jach »

dfox wrote: post #429
throwaway3neu94 wrote: post #396

Earlier quoted context omitted.

I think a passing test suite, no diff after clang-format, clean valgrind and clang-analyze checks are not too much to ask for. As long as the requirements are documented and the system is transparent and allows resubmission. But I agree there is a risk of academic instructors going way overboard in practice, e.g. by flagging actually useful minor standard conformance violations (like zero length arrays or properly #i…

My aversion to such systems is primarily motivated by the fact that every one of such system somehow penalized resubmissions. I probably don't have anything against "you have to write program that is compiled by this gcc/llvm commandline without producing any diagnostics and then passes this intentionally partially documented test suite". But in most cases the first part ends up meaning something like "cc -Werror -st…

In most of my courses that did something like this there was no resubmission.* The professor supplied a driver program, sample input the driver would use to test your program, expected output, and a Makefile template that gave you the 3 compilers + their flags that your program was expected to compile against and execute without issue. His server would do the compile-and-run for all 3 against the sample input and against hidden input revealed with the grade. He used the same compiler versions as were on the school lab computers.

* As a potentially amusing aside, a different course in a different degree program had a professor rage-quit after his first semester because he didn't want to deal with children -- he had a policy of giving 0s on papers with no name or class info on them, and enough students ("children") failed to do that correctly but complained hard enough to overturn the policy and get a resubmit.

Re: Git's list of banned C functions

#447

Post by mjcohen »

nanagojo wrote: post #331
paganel wrote: post #267

Earlier quoted context omitted.

This heavily filters for people who have had experience with programming in high-school or even before that, there's no way for a programming novice to pass that grueling routine. And then people rhetorically ask themselves why students coming from economically disadvantaged households are under-represented in this industry (one of the best paying industries in this time and age). Stuff like that has got to change.

> one of the best paying industries in this time and age Medicine is still better paid and better paid universally. Silicon valley is really the outlier here, most of Europe and the world programmers don't get paid that much in comparison.

Medicine also requires, after college, medical school and a residency - typically 6 to 9 years work. Programming requires none of this.

Re: Git's list of banned C functions

#448

Post by spc476 »

rightbyte wrote: post #263
Camillo wrote: post #130

Earlier quoted context omitted.

Many of the problems with C descend from a common root, the decision to use bare pointers (memory addresses) as the basic way to refer to strings, arrays etc. If they had used a {pointer, size} pair instead, it would have avoided all of these string problems, most buffer overflows, even the GTA Online loading problem that was on HN recently.

If they would have used a "fat strings" for the standard lib there would have been at least four different types by now with 8 to 64 bit lengths. Maybe even with signed char as length field on some systems, unsigned char on other. Or signed and unsigned for all int:s for a total of 8 types. I think the sentinel character was the best choice in hindsight and at the time in that regard. But I wish the xxx_s versions an…

There are no C standard functions, aside from malloc(), calloc() and realloc(), that have to allocate memory to work. I think that's intentional on the part of the C standard library.

Re: Git's list of banned C functions

#449

Post by EdwardDiego »

syncsynchalt wrote: post #211
kazinator wrote: post #195

Earlier quoted context omitted.

gmtime is just not thread-safe that's all, since it returns a static structure; gmtime_r is not banned.

Thanks, I am now a decade out of the C game and I was wracking my brain on what the problem with gmtime would be. My best guess was dodgy is_dst portability /shrug

Yeah, found this which explained it for me :)

https://lgtm.com/rules/2154840805/

Re: Git's list of banned C functions

#450

Post by mettamage »

nanagojo wrote: post #331
paganel wrote: post #267

Earlier quoted context omitted.

This heavily filters for people who have had experience with programming in high-school or even before that, there's no way for a programming novice to pass that grueling routine. And then people rhetorically ask themselves why students coming from economically disadvantaged households are under-represented in this industry (one of the best paying industries in this time and age). Stuff like that has got to change.

> one of the best paying industries in this time and age Medicine is still better paid and better paid universally. Silicon valley is really the outlier here, most of Europe and the world programmers don't get paid that much in comparison.

In The Netherlands this seems to be true. However, as a programmer you can work from home in many cases, especially now. So suppose that a junior psychiatrist makes 5000 EUR gross in NL [1] and a junior developer 2600 EUR gross [2].

A few things though:

1. A psychiatrist has to commute 1 to 2 hours per day. So that salary is not for 8 hours per day, but 9 hours at minimum. Adjusting their salary to an 8 hour basis, it needs to be multiplied by 8/9 or higher like 8/10.

2. The psychiatrist has to be on location. The cost associated with that is hard to quantify, but it is there. For example, I always sleep during the afternoon for 20 minutes, a psychiatrist can't do that. Also, I can take a break whenever I want, a psychiatrist can be on call for 24 hours straight in severe cases. Let's suppose this gives a cost of 1/16 as a multiplier (half an hour of extra work per day).

So the minimum overhead a psychiatrist has is 16/19, their salary is then 4200 EUR. This can be amazing or not so much, considering your own personal preference. My personal multiplier is 0.8 on top of all of this, so for me a 5000 EUR salary is worth 3360 EUR if it's working as a psychiatrist.

As a developer I experience something different, which is:

1. I do not have to commute, I can if I want to, but don't have to.

2. I do not have to be on location, nor do I have a strict schedule for going client after client. I can take random breaks during the day if it helps me be more productive.

So a developer's salary for 2600 EUR is much more like an actual 2600 EUR in that sense. Moreover, my personal multiplier for being a developer is a 1. There are some things I dislike and some things I absolutely love about being a dev (e.g. being a true netizen in the sense that you can randomly act with APIs if you want to).

To conclude: the absolute values are far apart, but the relative values might not. It differs on a person by person basis, and I haven't discussed the whole picture of course (e.g. needing to stay sharp as a dev, I don't know how that works for psychiatrists).

[1] https://www.monsterboard.nl/vacatures/zoeken/?q=Psychiater&w...

[2] https://www.glassdoor.nl/Salarissen/junior-web-developer-sal...

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