The goal of this project is to compare several C libraries that provide some STL like capabilities of the C++ (container template) but are targeting classic C language. A STL like library for C is a C library providing several classic generic containers for the C language, like vector, list, sorted set, unordered_map, and so on.
A small benchmark to compare their performance is includes in the bench directory.
To do this, the same simple programs will be implemented by the libraries in the more straight-forward way possible, for different kind of containers and for different types. Then the API ergonomics of each programs can be compared each other according to the user taste.
Objective characteristics of the libraries are directly compared in this file.
I am the main author of M*LIB, one of theses libraries.
This work is still a WIP.
The test program shall respect the following conditions:
- it shall use a basic type (int), a non POD type (the type mpz_t of the GMP library) and a string as the primary type of the container.
- it shall not comment the code (the code is assumed to be clear on what it does by itself) except if there is some workaround,
- it shall not produce any compilation warnings,
- it shall execute properly,
- it shall not leak any memory,
- it shall abort on error,
- it shall link dynamically with the GMP library (https://gmplib.org/) if needed,
- it shall link statically with the container library if needed,
- if a dynamic string container exists in the container library, it shall be used instead of a C string,
- the optional assertions shall be turned off.
A workaround is defined as a way to implement this program which is not natural for the library. This typically includes:
- create wrapper structure,
- create wrapper functions or macros,
- accessing internal fields of the containers (typically for using the qsort function).
For example, if a container library manual requests to define some macro for its use, then it won't be considered as a workaround.
The program shall perform the following operations:
- declare a dynamic array of int (resp. mpz_t, a string),
- initialize this array with the small unsigned integers values 17, 42 and 9 (performing a conversion from unsigned integer to mpz_t for GMP) or the constant strings "Hello", "World" and "!" for strings,
- sort this array,
- iterate the array to print the values.
The program shall perform the following operations:
- declare a non-ordered associative array from int (resp. mpz_t, a string) to (resp. mpz_t, a string),
- initialize this array with the association of signed integers values 17 to 4585, 42 to 4856 and -9 to 1452 (performing a conversion from signed integer to mpz_t for GMP) or the strings "Hello" to "LIB", "Welcome" to "Program" and "Sincerely" to "Your map" for strings,
- search for the key "Hello" and display it if successful,
- iterate the associative array to print the values.
The different programs are available in this repository. To build then, you just need to have a working C11 compiler, a make tool, git the GMP library, and the GLIB library to build then.
Simply run "make" to perform a clone of the projects and generate the different executables.
The following characteristics are used to compare the different C libraries. The C++ STL is also included as as reference.
- What is the supported C language (C89, C99, C11 or C23)?
- Is it a pure C program (no need for external preprocessor)?
- Is it a Header only library?
- How is implemented the Generic mechanism? By using A)void pointer, B)macro, C)_Generic and macro, D)intrusive field, E)code generation by include, F)code generation by macro
- Is-it type safe (aka. using an incompatible type produces at least a compilation warning)?
- support of integer/floats as basic type,
- support of struct POD data as basic type,
- support of array as basic type,
- support of object like data (needing custom constructor, destructor...) as basic type,
- support of C++ class as basic type,
- support of copy semantics: containers don't steal the ownership of the object given as parameter (passing an object data to a container will create a proper copy of the object data as per the object semantic),
- support of move semantics: containers steal the ownership of the object given as parameter,
- container / basic type spatial separation: the association of the methods of the basic type to the needed operators of the container library can be defined when the basic type is defined (ensuring spatial coherency of the basic type) and not only when the container is defined,
- support of an adaptation layer to transform the interface of the provided method to the expected interface of the operator,
- support of basic 'emplace'
- support of multiple, enhanced 'emplace' based on the initialized arguments,
- support of iterator abstraction
- support of sort algorithm
- support of sort algorithm with custom comparison,
- support of single linkage definition (use of declaration only for all files except one than include the container definition),
- full abstraction of the container type (user shall not use internal fields)
- contract violation checks (assertions on invalid inputs, on input contract violation or error reporting)
- natural usage of array (using of [] operator on the object)
- basic type is stored in the array, not a pointer to it.
- don't need explicit instanciation of the array with the basic type,
- functions are properly prefixed,
- error handling (return code, exception, abort, none)
- On exception, destructors of objects on stack are properly called.
- custom memory functions
- optional per-container context for custom memory functions
- support of forward declaration of container
- support of serialization (JSON, XML)
| Characteristics | STL | M*LIB | STC | CMC | CTL | CollectionsC | CC | GLIB |
|---|---|---|---|---|---|---|---|---|
| C language | NA | >=C99 | >=C99 | >=C99 | >=C99 | >=C99 | >=C11* or >=C23 | >= C89 |
| Pure C | NA | Y | Y | Y | Y | Y | Y | Y |
| Header only | Y | Y | Y | Y | Y | N | Y | N |
| Generic mechanism | template | F | E | F | E | A | C | A |
| type safe | Y | Y | Y | Y | Y | N | Y* | N |
| integer/float support | Y | Y | Y | Y | Y | Y | Y | Y* |
| struct POD support | Y | Y | Y | Y | Y | N | Y | Y* |
| C++ class support | Y | Y | N | N | N | N | N | N |
| C object support | Y | Y | Y | Y | Y | N | Y | Y* |
| Copy semantics | Y | Y | N | N | N | Y | N | Y |
| Move semantics | Y | Y | Y | Y | Y | N | Y | N |
| container/basic spatial separation | Y | Y | N | N | N | NA | Y | NA |
| Adaptator Layer | N | Y | N | N | N | N | N | N |
| Basic emplace support | Y | Y | Y | N | N | N | N | N |
| Enhance emplace support | Y | Y | N | N | N | N | N | N |
| Iterator support | Y | Y | Y | N | Y | Y | Y | N |
| Sort algorithm | Y | Y | Y | N | Y | Y | N | Y |
| Enhanced Sort algorithm | Y | Y | Y | N | Y | Y | N | Y |
| single linkage definition | N* | Y | Y | Y | N | Y | N | Y |
| Full abstraction | Y | Y | N | Y | N | Y | Y | N |
| Contract violation checks | Y | Y | N | N | N | N | N | N |
| Natural usage | Y | N | N | N | N | N | N | N |
| Basic type is stored | Y | Y | Y | Y | Y | N | Y | N |
| No explicit instanciation | Y | N | N | N | N | Y | Y | Y |
| prefixed function | Y | Y | Y | Y | Y | Y | Y | Y |
| memory handling | exception | abort, exception | retcode | retcode | none | retcode | retcode | retcode |
| destructors on exception | Y | Y* | NA | NA | NA | NA | NA | N |
| custom memory support | Y | Y | Y | Y | N | Y | Y | N |
| context for custom memory support | N | Y | Y | N | N | N | N | N |
| Forward declaration support | N | N | Y | N | N | N | N | N |
| Serialization | N | JSON | N | N | N | N | N | N |
- C11*: means C11 + extension
- Y*: Yes with some limitations.
| Comparison programs | STL | M*LIB | STC | CMC | CTL | CollectionsC | CC | GLIB |
|---|---|---|---|---|---|---|---|---|
| int:number of characters | 236 | 370 | 558 | 1011 | 593 | 885 | 611 | 696 |
| int:number of line of codes | 12 | 16 | 28 | 36 | 22 | 35 | 31 | 36 |
| int:number of workarounds | 0 | 0 | 0 | 2 | 2 | 1 | 1 | 0 |
| mpz:number of characters | 261 | 500 | 1222 | 1740 | 1407 | 1337 | 1120 | 840 |
| mpz:number of line of codes | 13 | 18 | 37 | 52 | 37 | 58 | 40 | 45 |
| mpz:number of workarounds | 0 | 0 | 3 | 7 | 5 | 1 | 2 | 0 |
| Containers | STL | M*LIB | STC | CMC | CTL | CollectionsC | CC | GLIB |
|---|---|---|---|---|---|---|---|---|
| Singly Linked Non-Intrusive list | Y | Y | N | N | Y | Y | N | Y |
| Doubly Linked Non-Intrusive list | Y | N | N | N | Y | Y | Y | Y |
| Singly Linked, Dualy Push Non-Intrusive list | N | Y | Y | N | N | N | N | N |
| Singly Linked Intrusive list | N | N | N | N | N | N | N | N |
| Doubly Linked Intrusive list | N | Y | N | N | N | N | N | N |
| Dynamic array | Y | Y | Y | Y | Y | Y | Y | Y |
| Static array | Y | N | N | N | Y | N | N | N |
| pair | Y | Y | N | N | N | N | N | N |
| tuple | Y | Y | N | N | N | N | N | N |
| optional | Y | Y | N | N | N | N | N | N |
| variant | Y | Y | N | N | N | N | N | Y |
| bitset | Y | Y | Y | Y | N | N | N | N |
| Dynamic character string | Y | Y | Y | N | Y | N | N | Y |
| string_view | Y | N | Y | N | N | N | N | N |
| deque | Y | Y | Y | Y | Y | Y | N | Y |
| queue | Y | Y | Y | Y | Y | Y | N | Y |
| priority queue | Y | Y | Y | Y | Y | Y | N | N |
| stack | Y | Y | Y | N | Y | Y | N | N |
| Bounded Queue | N | Y | N | N | N | N | N | Y |
| set | Y | Y | Y | N | N | Y | N | Y |
| multiset | Y | Y | N | N | N | N | N | N |
| map | Y | Y | N | N | Y | Y | N | N |
| multimap | Y | Y | N | N | N | N | N | N |
| unordered_set | Y | Y | Y | Y | Y | Y | Y | N |
| unordered_multiset | Y | N | N | Y | N | N | N | N |
| unordered_map | Y | Y | Y | Y | Y | Y | Y | N |
| unordered_multimap | Y | N | N | Y | N | N | N | Y |
| flat_set | Y | N | N | Y | N | N | N | N |
| flat_multiset | Y | N | N | Y | N | N | N | N |
| flat_map | Y | N | N | Y | N | N | N | N |
| flat_multimap | Y | N | N | Y | N | N | N | N |
| unique_ptr | Y | N | Y | N | N | N | N | N |
| shared_ptr | Y | Y | Y | N | N | N | N | N |
| advanced shared_ptr | N | Y | N | N | N | N | N | N |
| weak_ptr | Y | N | N | N | N | N | N | N |
| Function Object | Y | Y | N | N | N | N | N | N |
| Span | Y | N | Y | N | N | N | N | N |
| MDSpan | Y | N | Y | N | N | N | N | N |
| Bounded String | N | Y | N | N | N | N | N | N |
| Atomic Shared Register SPSC | N | Y | N | N | N | N | N | N |
| Atomic Shared Register MPSC | N | Y | N | N | N | N | N | N |
| Atomic Shared Register SPMC | N | Y | N | N | N | N | N | N |
| Atomic Shared Register MPMC | N | Y | N | N | N | N | N | N |
| Skip List | N | N | N | Y | N | N | N | N |
| Sorted Bidirectional Map | N | N | N | Y | N | N | N | N |
| Tree | N | Y | N | N | N | N | N | N |
| Algorithms | STL | M*LIB | STC | CMC | CTL | CollectionsC | CC | GLIB |
|---|---|---|---|---|---|---|---|---|
| TODO | Y | Y | Y | N | Y | Y | Y | Y |
The used versions are:
| COMPONENT | VERSION |
|---|---|
| GCC | 10.2 |
| C Macro Collections | v0.23.1 |
| CollectionsC | ff1be366329e2c82cd85b2c803114ef8d2115f7f |
| CTL | 3923e6776a231e5d58cf91225ca8a1d61879401b |
| M*LIB | a0818419ab959e05517336e1bea699c1854b29f3 |
| STC | 5fb5ed08250b5ad4eadd6e7a9fdc44f4519b15ff |
| CC | 2012d9d2eb8f035d7dc69f36ec03ca3199ede1bf |
| GLIB | 2.74 |
This is a WIP, and some reviews are needed to help this comparison.
If you see any mistakes in this report, or want to include another C library, or want to include another point of comparison, do not hesitate to open a pull request.
The bench directory contains a small benchmark comparing the performance of different libraries. Results are available here