Essential C (2003) [pdf]

http://cslibrary.stanford.edu/101/EssentialC.pdf

by kercker • 10 years ago

228 89 10 years ago

cslibrary.stanford.edu

cbd19846• 10 years ago

This predates the stdint.h header, which gives you int32_t and so on.

_kst_3• 10 years ago

Sort of. The copyright is 1996-2003. <stdint.h> was introduced in the 1999 ISO C standard.

But as of 2003, support for C99 wasn't very widespread, so omitting <stdint.h> was understandable.

npx• 10 years ago

Yeah, that was my first thought after a cursory reading, y u no <stdint.h>? There seems to be a lot of great content regardless.

I'd love to see an updated version.

aninteger• 10 years ago

Nice to see strlcpy in there. How do we get it into glibc?

_kst_3• 10 years ago

Even nicer to see that it warns users away from strncpy.

nwmcsween2• 10 years ago

strlcpy returns offset of dst + len of src which requires strlen(src) which isn't optional and sort of sucks imo. Something very similar but that doesn't do strlen(src) such as https://godbolt.org/g/Etpuhz would be better.

dimman• 10 years ago

Well one could argue that in C a string is not a string unless it's NUL terminated...

It's a choice they made to make it easy to detect truncation. If you don't care about the return value of strlcpy you can modify it to skip that part (which IMO will make it worse) but get rid of traversing src until \0 is found.

If you know you're working with non-terminated "strings" then just use memcpy instead.

If you're using proper functions you shouldn't end up with a non NUL-terminated string in the first place, although there are shortcomings in the commonly used libraries here unfortunately yes. It's hard to create a function that solves all problems.

(Side note: IMO The return value of latest OpenBSD version of strlcat (cat not cpy) is a bit weird when size is smaller than strlen(dst))

e19293001• 10 years ago

I've gone through a lot of exercises[0][1] from this site especially on how to implement a linked list in C. The time spent from the tutorial was absolutely worth while. I feel happy and satisfied with my self after solving one problem at a time.

For those who already know the syntax of C but wanted to learn more, the links I mentioned is a good exercise and opens up a lot of possibilities on what you can implement. You'll soon be able to realize the importance of linked list and why you'll want to use a linked list instead of just plain arrays.

[0] http://cslibrary.stanford.edu/103/LinkedListBasics.pdf

[1] http://cslibrary.stanford.edu/105/LinkedListProblems.pdf

conceit4• 10 years ago

To the contrary, linked lists are cache killers and hardly used nowadays. Or so they say on here, if I understand correctly.

huhtenberg• 10 years ago

hardly used nowadays

https://github.com/torvalds/linux/search?utf8=%E2%9C%93&q=IN...

That's unbearable. They should just redo this in JavaScript. That's what everyone uses nowadays. Or so they say on here, if I understand correctly.

jnbiche• 10 years ago

Linked lists are the default "goto" data structures for Haskell and many other functional languages, such as Lisp.

oselhn• 10 years ago

Some operations are faster on linked list than on vectors (insert on beginning, or on specified iterator position, delete iterator position). They also use less memory in some use cases. I was once optimizing transactional tree structure which internally used std::vector in each node. In most real use cases there was just one item in each vector, but vector preallocated 16 items. So changing to linked list lowered memory consumption significantly without measurable performance impact. The same applied for hash table vs. RB tree. All basic data structures can be useful, you just have to choose proper one.

gradschool• 10 years ago

IMHO, linked lists can be useful in conjunction with other data structures without hurting performance too much. An open hash table with a linked list in each bucket need only involve pointer chasing in case of collisions, which can be made arbitrarily rare by making the number of buckets large enough. In this way, there's a graceful performance degradation under unexpectedly heavy loads rather than hard limitations. I would be interested to read well informed contrasting opinions.

coherentpony• 10 years ago

Sweeping statements like this are almost always unilaterally false.

The best data structure or algorithm to use is usually problem-dependent.

goldbrick• 10 years ago

How on earth can you make such a statement about a fundamental data structure? Please, take CS101 before you you start throwing these kind of assertions around.

DonaldFisk• 10 years ago

My favourite language is Lisp, in which I use "linked" lists all the time, but I never use them in C. Use of lists without a garbage collector and either dynamic typing (as in Lisp) or strong static typing (as in Haskell) is a pain, and C has none of these built in. This means that, in C, you need to allocate memory every time you add something to your list, and hold the pointer to it in order to free it later. You also need to keep track of which types are stored, and where.

If your problem requires a lot of list processing, use a language more suitable for it. Otherwise, use extensible arrays, which are easy to implement in C.

conceit also pointed out that lists also increase the likelihood of cache misses, which slows down the program a little bit. Many C programmers care about that. I don't share their priorities - it is important to me, but less so than correctness, ease of programming (allowing more time for exploration and finding a more efficient algorithm), and response times.

kayamon• 10 years ago

Meh, sometimes there are easier ways than GC.

Just allocate all the list items from a big pool of memory that you own. When you're done, throw the whole lot away in one go. Languages like C++ tend to encourage micromanagement of data but it's not the only way to do things.

camperman2• 10 years ago

'char ASCII character -- at least 8 bits. Pronounced "car".'

Pronounced 'car'? Bollocks. Pronounced char as in charred.

cbd19846• 10 years ago

Pronounced care as in the first syllable of character.

Nursie• 10 years ago

The first syllable of character sounds nothing like "care"...

corndoge• 10 years ago

Pronounced char as in care

mynameisnoone4• 10 years ago

Nope; it's not [care] and it's not [kahr], it's [chahr].

It's as noob as when someone pronounces nginx [njinkx] instead of [engin-x], or linux as [li-nux] instead of [lin-ux].

_kst_3• 10 years ago

"Like the first word of "char *". The accent is generally on the first syllable."

C Infrequently Asked Questions #19.26, https://www.seebs.net/faqs/c-iaq.html

robert_tweed3• 10 years ago

I too pronounce it that way, since I learned C from books and just read it as it was printed.

I later noticed some people do pronounce it "car" which just seems odd. Why change it, if it doesn't save a syllable? It's not a truncation of how "character" is said either, because that's a different vowel sound.

Saying 'car' causes problems when learning C++, because all OOP examples on composition start "Car has-an Engine".

drivebyops• 10 years ago

Kernighan pronounces it care as in how you say character.

https://www.youtube.com/watch?v=de2Hsvxaf8M&t=2m35s

jasonjei• 10 years ago

Makes sense, as it's clearly an abbreviation for "character."

cannam2• 10 years ago

Thank you for that link.

I remember reading the "care as in character" thing years ago and just boggling at it -- who on earth makes character start with care? (As a British person, I think the first syllable of character rhymes with cat. There isn't a word that sounds like that but ending in r.) So rather than settle the question for me, it just dug the hole deeper.

Listening to Kernighan, I can just about hear what that remark meant.

(I say char myself, like the fish)

mbreese• 10 years ago

And how do you pronounce "varchar"?

I've always pronounced "char" as "car". Dunno why, I learned C from a book, so no one got to tell me I was wrong.

mynameisnoone4• 10 years ago

Well, it's wrong; varchar is pronounced [var-chahr].

bluedino• 10 years ago

Variable Character = Vare-care

Not that I say it that way, I've always heard and said var-char

broodbucket2• 10 years ago

I used to say "car", but it's definitely inferior to "char", since you can refer to char * as "char star" which is a lot of fun to say.

chris_wot2• 10 years ago

Make a variable that stores an ASCII character. Make it happy. Use it wrongly.

char grinned;

j_h_s• 10 years ago

I always have fun with char , I have a very specific cadence and melody I say it with (internally and externally). It's just such a fun phrase

tyingq• 10 years ago

How about varchar in sql land? Is that var-charr, or var-car ?

  char *var = "varchar";

mikestew• 10 years ago

Bollocks, pronounced char as in "char". I did not know this was even in dispute. Not that i care how anyone else pronounces it, i just thought it was blindingly obvious since we already have an English word spelled exactly the same as what we use in code to declare the thing.

mynameisnoone4• 10 years ago

Yup. It's [chahr] as in "I charred the steak.", not [kahr] because it doesn't have a horn and 4 wheels.

stevetrewick3• 10 years ago

Quite. Char as in 'nice cup of'.[0] Possibly delivered by a char lady. (Note, not a char woman, which is one's housekeeper).

[0] https://m.youtube.com/watch?v=eELH0ivexKA

camperman2• 10 years ago

Well yes, but saying pronounced char as in char doesn't really get the pronunciation across unambiguously, especially when half the world seems to pronounce it something else and Irishmen have their own spin ;)

mwfunk2• 10 years ago

I've always pronounced it as 'care', not because of how the identifier is spelled but because it's the first syllable of the word 'character'.

I don't think there's a consensus between car/char/care, though, even among C's creators. But if there was, I would vote for 'care'.

I always thought SQL was another weird one. When discussing the language itself, you can say 'sequel' or 'ess queue ell' interchangeably, but when referring to a database that has "SQL" in its name, there is a DB-specific one true pronunciation:

* SQL Server: 'sequel server'

* PostgreSQL: 'post gress queue ell'

* SQLite: 'sequel light'

* MySQL: 'my ess queue ell'

There's no complete consensus on any of those- just a preponderance of one, or an officially endorsed pronunciation in a FAQ someplace.

I've also heard 'my squeal' for MySQL, breaking out of the 'sequel'/'ess queue ell' duopoly altogether.

cmrx64• 10 years ago

Surely if there was consensus, you wouldn't get to vote.

robert_tweed3• 10 years ago

because it's the first syllable of the word 'character'.

Except the first syllable of 'character' is neither 'car' nor 'care', unless you have a really weird accent or are intentionally making fun of the English upper class.

PS: I always liked "squirrel" for SQL but sadly that one never got much traction.

jwdunne• 10 years ago

In my youth, I pronounced SQL as "squall". Quickly changed to "ess queue ell" when starting out professionally...

kafkaesq• 10 years ago

PostgreSQL: "postgres"

teddyh• 10 years ago

http://www.catb.org/~esr/jargon/html/C/char.html

char: /keir/, /char/, /kar/, n.

conceit4• 10 years ago

as in "carred" you mean? :P

sklogic• 10 years ago

Why? It's from "character", you do not want it charred.

rootbear• 10 years ago

Argument over GHif vs Jif in 3, 2, 1...

mynameisnoone4• 10 years ago

Don't use this. It's really rusty and teaches bad habits superseded by C99.

Here's a proper reference on C99 and C11:

http://en.cppreference.com/w/c

And see also reallocarray.

dave84• 10 years ago

Out of interest can you be more specific about the bad habits it teaches?

baby• 10 years ago

And is there a similar resource for current C standards?

partycoder• 10 years ago

For many of these examples, there's a debugger called "ddd" that can graph structures and can be useful.

stevetrewick3• 10 years ago

I want to love ddd, really I do, conceptually it is awesome and beautiful. In practice it is (IME) buggy (almost) to the point of uselessness. It's been a couple of years since I last used it, but it was last updated around 2009 :-(

exDM693• 10 years ago

ddd isn't my day-to-day debugger but I sometimes break it out when I need to visualize a data structure or keep track of multiple values when doing some more difficult debugging tasks.

It's far from perfect but still a useful tool.

jandrese• 10 years ago

I'm in the same boat. I've tried it out a few times and it's always a crashy mess. I want to like it, but the project seems to have been abandoned in a barely usable state.

eplanit• 10 years ago

This is an enjoyable comment section (rare to say). The arguments about the pronunciation of the char keyword is all part of being C programmers. This is great. :-)

Xophmeister2• 10 years ago

The "C Programming Cleverness and Ego Issues" is a good bit of advice:

Build programs that do something cool rather than programs which flex the language's syntax. Syntax -- who cares?

Otherwise, I'd never heard of/seen the `#pragma once` preprocessor directive. (Not that I do that much C programming!) How common is it to use this over include guards?

exDM693• 10 years ago

How common is it to use this over include guards?

Not very. It works in Microsoft's C compiler but can't be relied on elsewhere.

Xophmeister2• 10 years ago

Then why mention it over include guards, which are not discussed. Is Stanford a Microsoft shop, so to speak?

claudius• 10 years ago

It depends. Clang, GCC and the Intel C++ compiler all support #pragma once perfectly. Personally, I prefer it, as it is only one line rather than three and I don’t have to think of a unique name for the header guard. Supposedly it breaks if you play weird tricks with the filesystem (s.t. the compiler thinks two identical files are actually different), but I have never encountered such breakage.

thatsadude• 10 years ago

This and "C traps and pitfalls" [1] were my favorites back to the days.

[1] http://www.literateprogramming.com/ctraps.pdf

Essential C (2003) [pdf]

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