Is there a good string-manipulation C library?
https://github.com/antirez/sds
However the moment you call into other C libraries, they naturally only expect a char *.
WG14 could naturally work into something like SDS for strings and arrays, but of course that is out of their goals to ever do that.
Maybe it is, but even if it were, sds strings are a poor choice. I used them extensively in a private project.
1. Typedef'ing `sds` to a pointer type. This leaves no indication to the reader of code that any `sds` typed variable needs an `sdsfree`. IOW, for every other standard type it is clear when the data object needs a `free`, `fclose`, etc. This is a big deal, it's difficult to change the typedef for sds due to the way it returns pointers.
2. Not compatible with current string functions, strike 1: storing binary data in the strings, like the nul character makes it silently lose data when used with current string functions that accept `const char *`. This is a very big deal!
3. Not compatible with current string functions, strike 2: an sds string is only compatible with current string functions that take a `const char *`. This isn't such a big deal (for example, it provides a replacement for `strtok` as the standard `sds` type won't work for `strtok`) but it's unnecessarily incompatible.
4. With the current way it's exposed to a caller, you cannot use `const sds` variables anywhere, which removes a lot of compiler-checking. Trying to use `const` on any sds variable is pointless as you get none of the error-checking.
While sds solves many problems with raw C strings, those problems can be solved by adding standard library functions that work with existing C strings. In addition, it adds a few more problems of its own.
When they exist as vocabulary types, the ecosystem can rely on their existence and slowly adopt their use, similarly to threads support introduction in C11, for example.
Well, yes, I'd love to see some proper string support too, so at least we're in agreement about that :-)
But, overhauling C with additional (memory-safe) array types and string types that are nonetheless still compatible with legacy uses is probably a non-starter anyway. The only way forward would be to add a new type that isn't compatible, which is unpalatable to a lot of people (myself included).
Adding memory-safe functions and/or semantics is easier, but will probably not cover 100% of the memory-safety desired.
> When they exist as vocabulary types, the ecosystem can rely on their existence and slowly adopt their use, similarly to threads support introduction in C11, for example.
Threads, I feel, are a poor example for two reasons: 1) Hardly any code uses the `thread_t` type for a variety of reasons, and 2) There was no need for a `thread_t` type to be backward compatible with anything.
Already in use for a decade in Solaris SPARC, and eventually mainstream across all variations of ARM CPUs.
Unfortunely Intel botched their MPX implementation and now it is gone.
'const char *' arguments work just fine as parameters in libraries, and I don't see much of a use case (and insteaad more hazards) for a library that "resizes" a string argument destructively (like std::string does). The typical way to go about this is for the library to make a copy of the input string. On API boundaries, for memory that is needed longer than the function call lifetime, it is almost always an excellent idea to simply copy it. For data that doesn't make sense to copy (be it because of size or because only one side really needs it), the data should instead simply be created on the right side of the fence from the beginning.
I don't see myself needing a standardized string type because I'm not passing around string "objects", or concatening them, like it would be done in quick and dirty scripts. I honestly can't recall where that kind of thing would have been a good idea for my work in the last couple of years, and I'm much in favour of not growing the standard out of proportion. As said, if you desire C++ kind of ergonomics and want to solve more scripting-like tasks, there is already C++ and a ton of other languages.
What I can recall is skimming through a lot of C projects over the years that tries to do object-oriented and scripting type programming in C (often it wanted to be C++ or Java or even Python but it had to be C for some external reason), and that code is always, invariably, an unmaintainable mess where it's impossible to have a level of confidence that there are no memory errors and leaks. C is simply not suited for that style of programming.
It should be obvious that most "string" APIs from libc like strcat, strcpy, but especially strtok are ridiculously bad and are only in the libc because of history. Don't use them.
Even strlen() is rarely a good idea to use, and you can (should?) replace strlen("abc") by sizeof "abc" - 1.
You will have to define "good". My string library[1][2] is "good" for me because:
1. It's compatible with all the usual string functions (doesn't define a new type `string_t` or similar, uses existing `char *`).
2. It does what I want: a) Works on multiple strings so repeated operations are easy, and b) Allocates as necessary so that the caller only has to free, and not calculate how much memory is needed beforehand.
The combination of the above means that many common string operations that I want to do in my programs are both easy to do and easy to visually inspect for correctness in the caller.
Others will say that this is not good, because it still uses and exposes `char *`.
[1] https://github.com/lelanthran/libds/blob/master/src/ds_str.h
[2] Currently the only bug I know of is the quadratic runtime in many of the functions. I intend to fix this at some point.
Using go, I thought I was getting back to low level stuff but this C experience made me appreciate strings in Go. Web servers in C are crazy bad idea, especially if they are spitting out html. Lisp would be better. Node would be better. Go would be better.
So why didn't you use one of the bazillion library functions or third party libraries that terminate strings for you?
I feel like most of the criticism is coming from people who punish themselves by rejecting library functions and then telling that strings are hard. Doh.
It just doesn't feel fair to criticize C without mentioning that your experience comes from working under such unusual constraints. "Strings are hard, C sucks" is quite different from "strings are hard, C sucks when you can't rely on libraries." Also feels unfair to say you get crickets when you ask for a lib but actually you weren't even willing to use one. (There are tons of string libraries for C, it's impossible to miss them if you look around.)
Even then, if you're stuck working with only libc and your own code, there's a very high chance you're doing something wrong if you're doing math on strings and terminating them manually. There's a fair selection of libc functions that do all the math for you and will always output a properly terminated string if your inputs are a buffer & valid size and strings.