Beej’s Guide to C Programming [pdf]

http://beej.us/guide/bgc/pdf/bgc_usl_c_1.pdf

by tumblewit • 5 years ago

507 170 5 years ago

beej.us

tumblewit• 5 years ago

From the creator of the famous Network programming in C guide.

Flex247A• 5 years ago

Thank you for posting!

blunte• 5 years ago

IMO, pointers are less difficult to comprehend than other abstractions, like lambdas are.

If you know how to walk down a street and stop at the right street number, then you have used pointers. And if you've ever observed that one tall building may "cover" a range of street numbers, such as 200-220, then you should understand how to move from one 4-byte "value" to the next in an array in memory.

Anyway, many more analogies... probably better than this one.

Maybe unions could make using pointers a bit more challenging, but again, tall buildings next to short buildings and so on. We do this kind of pointer calculation in real life.

atoav• 5 years ago

What pointers basically are is not particularly hard to grasp. What is harder to grasp it what can be done with them and how you can shoot yourself in the foot with them in non-obvious ways.

I think I only understood much of it once I learned Rust, because you realize: Ah, that thing I once did in C is something that maybe ahouldn't be possible at all without extra steps. Even if I were to nwver use Rust again, this definitly helped to understand how to use pointers more safely.

chasil• 5 years ago

I think that pointers are a tool to control a CPU's indirect addressing modes from a higher-level language.

Exposure to an assembler makes pointers easy to understand.

qsort3• 5 years ago

What's difficult to understand about pointers isn't the concept of a pointer itself, or even * and &, it's the fact that working with pointers requires you to simultaneously understand different abstraction levels. While it's not unique to pointers, and it's in fact the case for most nontrivial programming tasks, what's unique about C is that pointers are so pervasive you can't really do anything if you don't understand how to work with them.

IME languages like Python aren't any easier than C to work with (ignoring UB issues of course), but it's certainly the case that you can probably kinda sorta get your job done with Python even without understanding the first thing of what you're doing, and that's not happening if you write in C.

bluetomcat5• 5 years ago

In C, pointers require you to think deeply about the ownership and lifetime of any "allocated object" at runtime. How long does it live, who is responsible for the deallocation, how many pointers does your program hold to that object (dangling issues). Ultimately, it can lead to a cleaner design if these issues are taken seriously up-front.

unwind4• 5 years ago

These are good points. I can sometimes feel that Python is more pointer-y (?) than people expect, with stuff like:

    a = {"one": 1, "two": 2 }
    b = a
    b["two"] = 99
    print(a["two"])

The above prints 99, since "b = a" does not copy the value (the dictionary) but just the reference to the value ("the pointer", kind of). This is surprising to some people.

bluedino2• 5 years ago

People that can’t comprehend arrays/lists in Python, especially multi-dimensional ones, would have had no chance in C

cassepipe4• 5 years ago

Pointers aren't that complicated but C syntax is misleading imho until someone comes along and tells you that the declaration syntax "follows use", which does not seem like the greatest idea. Then you get used to it and forget about it but when you don't know the principle behind declaration syntax, it does not help you reason about the language.

young_unixer• 5 years ago

Yup. I spent a ton of time trying to make sense of pointer syntax (* operator/modifier), until I realized that it didn't really make sense (except for the simplest cases) and then I could get on my life.

ZoomZoomZoom2• 5 years ago

Pointers seem easy until you understand the pointers you're working with do not correspond with the basic hardware model you have in mind:

https://www.ralfj.de/blog/2018/07/24/pointers-and-bytes.html

https://www.ralfj.de/blog/2020/12/14/provenance.html

https://www.ralfj.de/blog/2019/07/14/uninit.html

jhgb2• 5 years ago

If you know how to walk down a street and stop at the right street number, then you have used pointers. And if you've ever observed that one tall building may "cover" a range of street numbers, such as 200-220

I see that as a European, I have virtually no chance to understand pointers using street numbers. :)

(Fortunately I've never had problems either with lambdas or with pointers.)

ricardobayes• 5 years ago

Like my professor used to say, if you ever saw a pidgeon, you know what vectors are.

mytailorisrich2• 5 years ago

C is an abstraction over assembly, really (benefits being that it is simpler by being more abstract and portable across CPU types).

I've always thought that an introduction to CPUs (can take a simpler one as example) and how they work, how memory is (usually) organised, and to assembly would go a long way in helping understand many programming issues and C.

My experience is that C or programming concepts are often taught in a very abstract/mathematical way, which can be hard to grasp compared to a more practical approach.

If you take a concrete example where memory is effectively an array and indices are addresses (which holds true for most cases and, in any case is a good example) then understanding pointers becomes basically common sense and notations are simply conventions of the language you're using.

Arch-TK5• 5 years ago

Treating C as an abstraction over assembly is a surefire way to step into all the thousands of sharp edges C has. In fact I would hazard a guess that the majority of bugs found in software written in C are a result of programmers treating it as a portable assembler instead of a language for programming an abstract machine. So many incorrect assumptions arise as a result of telling people to treat C as a portable assembler that I think it's safe to call it an extremely bad bit of advice.

augustk2• 5 years ago

For anyone who wants to learn about pointers I can recommend studying a language simpler than C like for instance Oberon where pointers are more restricted. Having a look at Oberon can also broaden your view even if you know pointers in C.

  https://www.miasap.se/obnc/oberon-report.html
  http://people.inf.ethz.ch/wirth/Oberon/PIO.pdf

Koshkin3• 5 years ago

Actually, this could confuse things even more, because the C pointer and Oberon's POINTER TO have very little in common.

mumblemumble2• 5 years ago

Pointers are like swazzles[1]. The construction is very simple. The principle behind how they work is very simple. Learning how to use one well enough that you can (a) consistently make it do what you want, and (b) not injure yourself in the process, though, is no mean feat.

[1] https://www.atlasobscura.com/articles/swazzle-punch-and-judy

chowells• 5 years ago

Well, you've demonstrated that memory addresses aren't that hard. But you've also demonstrated how easy it is to get undefined behavior in C programs.

C's pointers aren't memory addresses. Ok, they tend to be represented as such at run time, but that's not what the spec actually says the are. And as far as compiler authors are concerned, they can do anything they want as long as it's within spec. Further, the spec even requires some additional behaviors pure memory addresses aren't capable of. See https://www.ralfj.de/blog/2020/12/14/provenance.html for examples of the extra requirements.

Compared to that mess, lambdas are trivial. They're just functions.

aphrax3• 5 years ago

I've enjoyed this guide a number of times but each time I hit a brick wall trying to understand pointers. I'm still keen to learn but it just doesnt 'click' for me...

Edit: poor grammar

sanedigital• 5 years ago

One analogy I’ve used to teach pointers is to think of them as phone numbers. They’re an identifier used to get ahold of something that you might not otherwise know exactly where it is. If you call my number, I’ll pick up. But if I transfer my number to someone else, that doesn’t mean anything happened to me personally. That number is just not pointing to new anymore.

unwind4• 5 years ago

That is fascinating, thanks for sharing. What part of pointers is it that makes it so hard for you to grasp, if you have any thoughts?

Do you have any experience in other programming languages? How familiar are you with low-level computer architecture, at the CPU/memory level?

I guess one important part is to realize that in C, variables are basically names for memory locations, that in turn hold values. In other languages variables can be more abstract, and you have no idea how the value(s) are being associated with the variable name.

I started writing an example here, but I ran out of time and it wasn't good enough. :) Sorry.

EDIT: Now I've taken a loo at the relevant pages in the guide itself, and it seemed to explain the concepts very clearly and easily, so ... I'm not sure how to help. :)

aphrax3• 5 years ago

Thanks for this - I think you are on to something when you mention the low level architecture, on reflection this is where I need to fully understand the concepts - I'm messing around in this area with the usual (Nand to Tetris) type info/tutorials. I'll then come back to this manual I'm sure. Like I say - I've enjoyed it quite a bit. Its certainly me lacking - not the book!

sedeki• 5 years ago

Try to explain where you're stuck.

redis_mlc2• 5 years ago

Just learn C by reading and working through the K&R book. (It's one of the best CS books ever written.)

https://www.amazon.com/Programming-Language-2nd-Brian-Kernig...

Also, there's nothing magical about pointers - scripting languages use "handles", which is the same thing except they're read-only to the end-user programmer.

The real challenge with C is multi-threaded programming, so don't do that if you don't need it.

dvfjsdhgfv• 5 years ago

Just learn C by reading and working through the K&R book. (It's one of the best CS books ever written.)

This is really an amazing feat: books on programming languages age really fast. This one - not so much. And you can really appreciate the careful thought that was put in each sentence. Peerless.

The real challenge with C is multi-threaded programming, so don't do that if you don't need it.

Well, these days it's harder and harder to avoid it if you want to write efficient apps - we got more cores and the clocks remain more or less the same.

cassepipe4• 5 years ago

Personnally I have learned C following the CS50 course on Harvard's youtube channel and pointer came easily with http://alumni.cs.ucr.edu/~pdiloren/C++_Pointers/.

It's a great (free as in beer) start.

beej7112• 5 years ago

I agree. If you're only going to read one book, that's the book. :-)

bluetomcat5• 5 years ago

Just another integral data type which supports not only arithmetic (adding or removing an integral value), but also "dereferencing" which means getting a value of the pointed-to type at the pointed-to address.

The quantities added or removed in arithmetic operations are the same as the size of the type that is being pointed to.

shric2• 5 years ago

It's incorrect to call a pointer an integral type. It doesn't behave like an integer (you can't add two pointers together). You can't even subtract two pointers from each other unless they point into the same array (or one element past) without causing undefined behaviour. You can't even reliably convert a pointer generally to an integer and back again unless it's a void *.

Edit: just remembered I wrote a rambling on this in 2014: https://ramblings.implicit.net/c/2014/04/21/pointers-are-not...

1_player• 5 years ago

A pointer is a level of indirection.

A regular variable is a place in RAM that contains a certain value.

A pointer is a variable whose value is the address of another variable.

X = 5

Y = location in memory of X

Now you can use Y to manipulate X

DyslexicAtheist3• 5 years ago

around 25 years ago I got so frustrated because I hit the same brick walls over and over especially with advanced pointer stuff. It sounds silly today but what helped me are some really basic books about C. iirc the "for dummies" series and others.

It took another couple of years until I understood what I lacked wasn't time spent reading another section on pointers but additional tooling. Using a debugger and stepping through programs was the next breakthrough.

Looking back today understanding my C (on UNIX) isn't just the language it's a whole ecosystem of tools to measure what is going on and manipulating state so that I can troubleshoot. After gdb came valgrind, strace, lsof, signal handling (kill), process control, gcov, the appropriate type of CFLAGS to use (e.g. the compiler itself) and how to stay sane using Make.

None of them have to do with pointers but they make life a lot easier. To become productive at this takes years but becoming good took me decades. C (imho) isn't just another language but a complete career path with dozens of branches into other areas.

If you stay patient with yourself and treat it as a journey instead of a milestone it can deepen your understanding of systems (nod to eBPF) in situations many others will bail out long before.

Don't give up and then not much will look scary any more.

aphrax3• 5 years ago

Thanks so much for this reply, really quite inspiring. Much appreciated.

agumonkey• 5 years ago

Ability to inspect is vital indeed

quelsolaar3• 5 years ago

Try watching this: https://youtu.be/443UNeGrFoM

Its long and is filled with other stuff about C programming but it goes in to dept about how to think about pointers. Good Luck!

Koshkin3• 5 years ago

1) A pointer is a memory address of an object.

2) Pointer arithmetic takes into account the size of the type pointed to.

3) The asterisk operator gives you access to the object.

4) The ampersand operator gives you the pointer to the object.

If you understand this, you understand pointers. (The arrow operator is syntactic sugar.)

squarefoot• 5 years ago

Pointers are easy and fun, just keep experimenting with them. What is essential is understanding that they're nothing more than like a piece of paper containing where something is instead of being part of that something, and they're the same size of the address registers of the underlying hardware as they must be able to point everywhere in the addressable memory. Therefore, on a 32 bit system pointers will be 32 bits long, on a 64 bit system they will be 64 bits long, etc. no matter what they point to.

That is, both a pointer to a single byte and a pointer to a 10GB memory chunk will be of the same size because they just hold a memory location whose value represents where that data starts. Therefore, declaring pointers to a certain type doesn't change their size at all, it just becomes handy when one needs to go back and forth in a memory area in which objects of that type are stored one after another, so that incrementing or decrementing the pointer by a number actually means that number times the size of the objects. Imagine asking for directions to someone and he replies "3rd door" or "3rd building" or "3rd block"; he gave you a pointer that is always the same size, but how much you have to walk will depend on the destination (size).

Once grasped the above, it should become a lot more easy; I had the same problems, then one day had a flash and they became totally clear (and fun).

It may be of help experimenting with a debugger, or simply printf-ing all values a pointer assumes when declared, assigned, incremented/decremented etc. Keep also track of the pointed data values, changing it instead of the pointer, or the other way around, are common mistakes.

An old small command line program like "cdecl" can help a lot to understand complex declarations, and someone has even made an interactive webpage around it (cdecl.org).

example:

cdecl> explain char ((x())[]) () declare x as function returning pointer to array of pointer to function returning char

DyslexicAtheist3• 5 years ago

it actually has working examples for all of the C library calls even math routines. Not sure if it's complete but it seems so. This seriously helps bridging the gap between man (2) pages and putting things into working code and only beef I have is that I didn't have it 25 years ago. Very cool.

saagarjha• 5 years ago

Nit: most of the C library calls are in section 3; section 2 is system calls.

DyslexicAtheist3• 5 years ago

yepp (me facepalm)

beej7112• 5 years ago

It's not complete... There are tons of functions in C11+. I'm whittling it away.

Putting in the examples for all the calls--I stole that idea from The Turbo C Bible, a book I really loved back in the day... because of the examples.

yrgulation• 5 years ago

I commented this before on a previous post on one of beej’s guides: https://news.ycombinator.com/item?id=26100075

These tutorials are the gold standard of tutorials. I wish more content would be as straight to the point and easy to follow.

caseyavila2• 5 years ago

It’s especially insidious because once you grok pointers, they’re suddenly easy. But up until that moment, they’re slippery eels.

I'm sort of a C beginner myself. I understand pointers, and I do remember they clicked in my mind suddenly. The moment before, I didn't understand at all. I also love the quirkiness of this guide. Definitely going to give this a read.

andi999• 5 years ago

Do you mean the general concept or like: a is a pointer to an array of functions which return pointers to functions which return ints and take double arrays as parameters.

This somehow never really clicked (or actually it clicked and declicked somehow)

caseyavila2• 5 years ago

For me it was the practical understanding. I understood the concept of a pointer, but I wasn't confident in writing code that used that used them or (more importantly) reading code. I would see an asterisk, multiple asterisks, or ampersands, and would get confused with the code. I do think some of the issues I encountered had to do with the notation of pointers. The asterisk serving as a symbol to both declare a pointer variable and dereference one.

jmiskovic• 5 years ago

If you always read from right to left (and put occasional braces for readability) you can get through anything. Most tricky ones are in job interviews, while ones found in the wild will often make use of typedefs to break down the complexity.

signa11• 5 years ago

Jens Gustedt's "Modern C" (https://modernc.gforge.inria.fr) is an excellent resource as well.

k_sze• 5 years ago

Jens Gustedt is a co-editor of the ISO C standard, so he knows his shit. Modern C is probably the best book about modern C, short of reading the standard.

SAI_Peregrinus• 5 years ago

It's far easier to read than the standard, too, since it's explanatory rather than declaratory. The standard tells you what C can do, Modern C teaches you how.

gnuvince• 5 years ago

What does "modern" C imply? AFAIK, there are not very many new language features; is it about organizing code differently than what one would learn from K&R?

ashconnor• 5 years ago

C99 I would imagine: https://en.wikipedia.org/wiki/C99

mumblemumble2• 5 years ago

According to the introduction of the book, C17. Which is mostly just bugfixes on C11. But, compared to c99, you get nice things like generic expressions, better unicode, and (standard) multithreading.

beej7112• 5 years ago

I'm chuckling to myself at "there are not many new language features" because that's what I thought.

There's fair amount added to the core since C89, actually... And if you include the library changes, game over! I had no idea how much had been added.

More challenging is to find what's been subtracted.

This no longer defaults to int:

static i;

And gets() is toast.

Anyone know any others?

thamer• 5 years ago

Apart from the new features added in C11 or C17 that others have mentioned, both Beej's Guide and Modern C also cover threads and string encoding (neither of these topics are covered in K&R 2nd edition, as far as I remember). Beej's Guide also has a section on internationalization and one about date/time handling.

But yes, the code is also quite different than in K&R which is relatively terse. See for example this comment in K&R about strcpy on print page 105 (page 119 of the PDF)[1], where after showing two versions of strcpy that are pretty readable and easy to follow, the book says:

In practice, strcpy would not be written as we showed it above. Experienced C programmers would prefer

    void strcpy(char *s, char *t)
    {
        while ((*s++ = *t++) != '\0')
            ;
    }

Followed by a paragraph saying the condition could be simplified, and that

the function would likely be written as

    void strcpy(char *s, char *t)
    {
        while (*s++ = *t++)
            ;
    }

Make of that what you will :-)

[1] https://kremlin.cc/k&r.pdf#page=119

potbelly83• 5 years ago

Nice book. As a C++ programmer how much of its discussion related to C's storage/memory model would carry over to C++?

fctorial2• 5 years ago

All of it. C++ is a superset of C.

transient_47• 5 years ago

I stumbled upon this gem a while ago [0] while looking for a decent tutorial and reference to C:

Stuff that should be avoided: [...]

Beej's Guide to C: http://beej.us/guide/bgc/output/html/singlepage/bgc.html

Full of mistakes.

[...]

Could someone confirm this? I've seen a lot of threads here on HN praising beej's guides so I am somewhat confused.

[0] http://www.iso-9899.info/wiki/Main_Page

edit: Formatting

determinateproc2• 5 years ago

Beej himself lists this as an 'alpha-quality document' on the download page [0] and if I remember correctly, it has been so for years. Wonder why this is posted here on HN.

[0] http://www.beej.us/guide/bgc/

petee2• 5 years ago

I think posts like this are handy just for the extra exposure an alpha document might need; there's a lot of good feedback and discussion here that hopefully beej comes across someday and can finish the book

beej7112• 5 years ago

I recently overhauled it in a big way.. er, "am overhauling it".

And I'm sure it's full of mistakes. It's over 500 pages, most of which has yet to be edited, so if there are fewer than 1000 defects, I'd be shocked.

But I fix them all as I find them, or as they're pointed out. And after an eventual editing pass, things will be better.

And if it's not useful to someone, I take no offense I'd they don't like it. :-)

tom_mellior5• 5 years ago

On a quick skim of some introductory parts I found:

When you have a variable in C, the value of that variable is in memory somewhere, at some address. Of course. After all, where else would it be?

It would be in a register. Of course. Or it would be eliminated by a compiler optimization. Of course.

Same error later on:

When you pass a value to a function,a copy of that value gets made in this magical mystery world known as the stack

No. In most common cases, arguments will not be passed via the stack. This goes on to clarify in a footnote that the implementation might not actually use a stack, and that the stack has something to do with recursion. That part is true, but the values saved on the stack for recursing are not the same as function arguments.

Neither in the Variadic Functions chapter nor anywhere else are the default argument promotions mentioned -- this will bite someone who tries to write a variadic function that gets floats out of the variadic argument list, which you cannot do, since passing a float to a variadic function promotes it to double.

Speaking of floats... This is one of those tutorials that are very confused regarding their target audience. For example, in the "Variables" section it goes out of its way to define: "A “byte” is an 8-bit binary number. Think of it as an integer that can only hold the values from 0 to 255, inclusive." (which isn't the C definition, but this really is nit-picking) but then happily goes on to talk about Booleans and floats without explaining what those are. What reader has a background that would make this useful?

Overall, from the little I've seen, I'd give this an initial rating of "broadly correct but with definite mistakes".

Even if it were fully correct, I dislike the verbose style, and I wouldn't recommend this tutorial. For example, in the Hello World chapter, we have the following "explanation" of the line "#include <stdio.h>":

Now, what is this#include? GROSS! Well, it tells the C Preprocessor to pull the contents of another fileand insert it into the code rightthere.Wait—what’s a C Preprocessor? Good question. There are two stages (well, technically there are more thantwo, but hey, let’s pretend there are two and have a good laugh) to compilation: the preprocessor and thecompiler. Anything that starts with pound sign, or “octothorpe”, (#) is something the preprocessor operateson before the compiler even gets started. Commonpreprocessor directives, as they’re called, are#includeand#define. More on that later.Before we go on, why would I even begin to bother pointing out that a pound sign is called an octothorpe?The answer is simple: I think the word octothorpe is so excellently funny, I have to gratuitously spread itsname around whenever I get the opportunity. Octothorpe. Octothorpe, octothorpe, octothorpe.Soanyway. After the C preprocessor has finished preprocessing everything, the results are ready for thecompiler to take them and produceassembly code8,machine code9, or whatever it’s about to do. Don’t worryabout the technical details of compilation for now; just know that your source runs through the preprocessor,then the output of that runs through the compiler, then that produces an executable for you to run. Octothorpe.What about the rest of the line? What’s<stdio.h>? That is what is known as aheader file. It’s the dot-hat the end that gives it away. In fact it’s the “Standard I/O” (stdio) header file that you will grow to knowand love. It contains preprocessor directives and function prototypes (more on that later) for common inputand output needs. For our demo program, we’re outputting the string “Hello, World!”, so we in particularneed the function prototype for theprintf()function from this header file. Basically, if we tried to useprintf()without#include <stdio.h>, the compiler would have complained to us about it.How did I know I needed to#include <stdio.h>forprintf()? Answer: it’s in the documentation. Ifyou’re on a Unix system,man printfand it’ll tell you right at the top of the man page what header files are required. Or see the reference section in this book.:-)Holy moly. That was all to cover the first line! But, let’s face it, it has been completely dissected. No mysteryshall remain!

Only one sentence of this is relevant for an introductory Hello World chapter: "Basically, if we tried to use printf() without #include <stdio.h>, the compiler would have complained to us about it." None of the rest is relevant or helpful to a beginner who is just seeing their first ever C program. Also "completely dissected" isn't true either; there is a lot more to be said about headers.

fps_doug• 5 years ago

It would be in a register. Of course. Or it would be eliminated by a compiler optimization. Of course.

Since you mention relevance for beginners later on in your post I'd argue this isn't relevant either. This concept holds true for simple code that doesn't do advanced stuff like working with hardware. As soon as you do &variable, you get an address and can work with it. If the compiler optimized something away you never use you might as well just pretend it's in memory somewhere for the sake of a mental model that's easy to grasp. Same with passing variables via stack. A simple compiler could do it just like that.

That isn't to say the tutorial is good/not good, but these points in particular seem rather sane to me. Far from "Mastering C Pointers" at least :)

Const-me• 5 years ago

It would be in a register. Of course. Or it would be eliminated by a compiler optimization

As long as you’re taking, and using, the address of that variable, it’s almost guaranteed to be in memory. Even if it won’t, the compiler guarantees the output of the program will be equivalent to unoptimized code.

arguments will not be passed via the stack

I’m not sure explaining nuances of various calling conventions, and how they differ across processors and OSes, is useful information in a document about C and targeted towards beginners.

You’re talking about things which are underneath C in the abstraction layer hierarchy. The abstraction has many layers, the lowest one being quantum physics. One has to stop somewhere, and this article decided to stop at C, as opposed to assembly.

beej7112• 5 years ago

It's a tough line between intro and The Rabbit Hole. But I'll see what I can do there.

Appreciate the feedback. Some good suggestions here that I'll add.

Twisell• 5 years ago

Only one sentence of this is relevant for an introductory Hello World chapter: "Basically, if we tried to use printf() without #include <stdio.h>, the compiler would have complained to us about it."

Quite the contrary in my opinion. As a beginner I was very frustrated with most approach that say "Just put that thing that is needed and will be explained latter. And it work good job attaboy!"

And maybe 250 pages latter if the author didn't forgot in the meantime you get a one liner mention that link back to the first introduction of the syntax.

At least this guide don't let the reader in the fog wondering.

exceltior• 5 years ago

Thanks for sharing this

qwerty4561272• 5 years ago

Again, the string chapter is telling us about zero-terminated char arrays/pointers and doesn't even mention Unicode/UTF-8 or safety :-(

beej7112• 5 years ago

I do have a chapter on Unicode and wide characters, but it's separate from the "classic" strings chapter. That said, I could certainly refer forward to it.

And C11 only has minimal portable UTF-8 support, but I do talk about it. I think C21 will improve on that a bit.

A note on safety would be well worth it. I'll do that. Good suggestion.

qwerty4561272• 5 years ago

Cool. Thank you. Lack of coverage of this subject in educational materials has been pain ever since I was studied C at school. All the books said that: strings are zero-terminated char arrays. But this kind of strings is almost useless in today globalized world. Sorry I didn't notice you cover this topic in a separate chapter. This makes your guide really great. Let me suggest you mention that chapter in the strings chapter unless you have a reason to omit such a reference. Thank you for a great job!

emilengler• 5 years ago

A thing I really enjoy about this guide is that it’s close to common C paradigms and practices. Many guides lack this and only show outdated ones.

throws235772• 5 years ago

I haven't read these 2 books, but would like the opinion of someone who did.

[1] C Interfaces and Implementations: Techniques for Creating Reusable Software by David Hanson - HN's tptacek seemed to rave about this book, that's how I heard of it. Wonder what he thinks of it in 2021.

[2] C Programming: A Modern Approach by K. N. King - this one seems to be loved by many. Seems to be more 'beginner-friendly' than the 1st one I guess.

ZoomZoomZoom2• 5 years ago

You can always check reviews published by ACCU.org:

K. N. King "C Programming":

https://accu.org/bookreviews/1999/graham_1260/

Ben Klemens "21st Century C":

https://accu.org/bookreviews/2016/demin_1882/

Robert C. Seacord "Effective C":

https://accu.org/bookreviews/2020/glassborow_1952/

https://accu.org/bookreviews/2021/bruntlett_1959/

throws235772• 5 years ago

Wow I never heard of Robert Seacord's 'effective C'. Thank you.

Edit: Here's a short rationale for the book by the author.

https://ieeexplore.ieee.org/document/9237323

tptacek• 5 years ago

It remains my favorite C book, though: I don't think you should write much C anymore.

mrslave• 5 years ago

My favorite is Expert C Programming: Deep C Secrets by Peter van der Linden. I started it as soon as I encountered C at university and could only get through about a chapter at a time. By third year when the assignments in C got hard I was in a great position, partly for this book. Even crazier is I enjoyed it.

dimran• 5 years ago

This is a wonderful book if you want to understand how the OSI model of internet works, clearly illustrated network apis. Man this book was amazing.

cpach• 5 years ago

I think you’re confusing it with another book. This is a guide to C programming. You’re probably thinking of Beej's Guide to Network Programming :)

https://beej.us/guide/bgnet/

mnunez• 5 years ago

Just found out that it has an actively maintained GitHub repository, with 35 or more commits this April alone. https://github.com/beejjorgensen/bgc/commits/main

dcchambers• 5 years ago

Beej's Guide to Network Programming helped me survive a grad-level computer networking class as a naive undergrad in college.

If his guide to C is anywhere near as good it should be an awesome resource.

beej7112• 5 years ago

The C Guide is still rough around the edges (and even some in the center). But I'm working on it! :-)

billfruit2• 5 years ago

There was a "C Unleashed" book, a massive tome of 1000+ pages written by many famous programmers, many of them who where quite active in comp.lang.c, like Richard Heathfield and CB Falconer, had quite insightful material in it.

Any one remember the heyday of comp.lang.c? I wonder what goes on in there now.

mistertester• 5 years ago

Yes, usenet was huge for me back in the early 90s when I had questions on C programming. I would ask them on comp.programming.c and had some of the best programmers providing guidance. Of course they were strict with questions/discussions being specific to ANSI C.

beej7112• 5 years ago

I bought that book ages ago. Good stuff. comp.lang.c still has a small group of knowledgeable regulars, but a lot of the "old guard" seems to have stepped away. And Usenet is a shadow of its former self, obviously.

Reddit has more traffic nowadays.

bluedino2• 5 years ago

#c on EFnet!

ben_pfaff• 5 years ago

I wasn't sure anyone but the authors remembered C Unleashed! I wrote the chapter on binary search trees and balanced trees.

Comp.lang.c was important to me for many years. I've met 5 or so of the regulars at least once. The most famous comp.lang.c regular is probably Tim Hockin of the Kubernetes project.

billfruit2• 5 years ago

Thanks very much! The code from the book proved very useful since C does not have a standard library of rich data structures.

beej7112• 5 years ago

Ben Pfaff... There's a name I recognize from back then. :-)

dmitryminkovsky• 5 years ago

There was a thread about that group a few months ago and this post in particular really stuck in my mind: https://news.ycombinator.com/item?id=26127632

chubot• 5 years ago

That's what I remember from comp.lang.c -- lawyer-ly obsession with ANSI C, rather than C as it's being used. That is an important distinction which I respect, but they should have had some kind of sister forum that's more practical. They denied that hardware exists, etc.

Also, obsession with ANSI C, analogous to obsession with POSIX shell, is sort of "middlebrow" in the sense that the people who WRITE the spec need to go outside of it to create a new version of it. Good specs are derived from real usage.

rubicon33• 5 years ago

I love Beej’s guide to network programming. Back when I was just starting to learn to code, I wanted to get right down to the low level C stuff and his guide was what I used. It was simple and approachable and I had a running TCP client by the end of the day. It was a thrilling experience for a young novice.

Spivak• 5 years ago

Is there any guide that operates at the level of the C abstract machine and a real platform because it's always really jarring to have lots of hand-wavy statements like

When compiling C,machine codeis generated. This is the 1s and 0s that can be executed directly by the CPU.

No! Tell me about how the code is translated into an ELF executable, linked, has its memory laid out by the OS and then executed.

I’m seriously oversimplifying how modern memory works, here. But the mental model works, so please forgive me

No! Tell me about how memory works in the C abstract machine which is what you can actually program against and guaranteed by the compiler.

Nothing of yours gets called before main(). In the case of our example, this works fine since all we want to do is print a line and exit

No! tell that main is special because it's mapped to the _start symbol or at least eventually jumped into by code at that symbol which has an address that's stored by the linker in e_entry.

Like I might be the weird one but this kind of writing (which is common to seemingly all C texts) confuses me more than if it had just been explained.

3rly• 5 years ago

I see a lot of people making opinions that clearly shows that they have not audited the entire guide. For the intended audience that the author wanted to reach. I will say that he accomplished it.

For anything that one finds as mistakes, the author went out of his way (via references) for the reader to dig further.

dang• 5 years ago

It doesn't do the brisk business of the networking one, but there have been at least a couple past threads:

Beej's Guide to C Programming - https://news.ycombinator.com/item?id=26100391 - Feb 2021 (1 comment)

Beej's Guide to C Programming (2007) - https://news.ycombinator.com/item?id=15198093 - Sept 2017 (79 comments)

As long as we're talking C programming, I'd single out this large thread with C Standards committee members from last year:

Tell HN: C Experts Panel – Ask us anything about C - https://news.ycombinator.com/item?id=22865357 - April 2020 (962 comments)

enahs-sf• 5 years ago

I love C programming. Even though people say it's dangerous and easy to shoot yourself in the foot, It really is the simplest and most elegant way forward. That said, having to invent the wheel yourself so much, it is not as time efficient as some more modern languages.

I liken it to an artisanal craftsman's tool versus a modern multi-tool like a dremel which would be something like python.

seibelj• 5 years ago

Totally agree - sometimes I solve small problems in C rather than a scripting language. It feels like freedom and the result is so damn fast.

Beej’s Guide to C Programming [pdf]

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