VERSION 2.X RELEASED: This main version uses a different way to instantiate templated containers, and is not compatible with v1.X, however the usage is otherwise compatible with v1.X. The new style has multiple advantages, e.g. implementation does no longer contain long macro definitions to generate code. Also, specfiying template arguments is more user friendly and flexible.
A modern, templated, user-friendly, fast, fully type-safe, and customizable container library for C99, with a uniform API across the containers, and is similar to the c++ standard library containers API. For an introduction to templated containers, please read the blog by Ian Fisher on type-safe generic data structures in C.
STC is a compact, header-only library with the all the major "standard" data containers, except for the multimap/set variants. However, there is an example how to create a multimap in the examples folder.
- carr2, carr3 - 2d and 3d dynamic array type
- cbits - std::bitset alike type
- cdeq - std::deque alike type
- clist - std::forward_list alike type
- cmap - std::unordered_map alike type
- cpque - std::priority_queue alike type
- csptr - std::shared_ptr alike support
- cqueue - std::queue alike type
- cset - std::unordered_set alike type
- csmap - std::map sorted map alike type
- csset - std::set sorted set alike type
- cstack - std::stack alike type
- cstr - std::string alike type
- csview - std::string_view alike type
- cvec - std::vector alike type
Others:
- User friendly - Just include the headers and you are good. The API and functionality is very close to c++ STL, and is fully listed in the docs. The #define i_xxx-declarations configures the container type to use. You may define various names to customize element-comparison, destruction, cloning, conversion types, and more.
- Unparalleled performance - The containers are about equal and often much faster than the c++ STL containers.
- Fully memory managed - All containers will destruct keys/values via destructor defined as macro parameters before including the container header. Also, shared pointers are supported and can be stored in containers, see csptr.
- Fully type safe - Because of templating, it avoids error-prone casting of container types and elements back and forth from the containers.
- Uniform, easy-to-learn API - Methods to construct, initialize, iterate and destruct have uniform and intuitive usage across the various containers.
- Small footprint - Small source code and generated executables. The executable from the example below with six different containers is 22 kb in size compiled with gcc -Os on linux.
- Dual mode compilation - By default it is a simple header-only library with inline and static methods only, but you can easily switch to create a traditional library with shared symbols, without changing existing source files. See the Installation section.
- No callback functions - All passed template argument functions/macros are directly called from the implementation, no slow callbacks which requires storage.
- Compiles with C++ and C99 - C code can be compiled with C++.
Benchmark notes:
- The barchart shows average test times over three platforms: Mingw64 10.30, Win-Clang 12, VC19. CPU: Ryzen 7 2700X CPU @4Ghz.
- Containers uses value types
uint64_tand pairs ofuint64_tfor the maps. - Black bars indicates performance variation between various platforms/compilers.
- Iterations are repeated 4 times over n elements.
- find(): not executed for forward_list, deque, and vector because these c++ containers does not have native find().
- deque: insert: n/3 push_front(), n/3 push_back()+pop_front(), n/3 push_back().
- map and unordered map: insert: n/2 random numbers, n/2 sequential numbers. erase: n/2 keys in the map, n/2 random keys.
The usage of the containers is similar to the c++ standard containers in STL, so it should be easy if you are familiar with them. All containers are generic/templated, except for cstr and cbits. No casting is used, so containers are type-safe like templates in c++. A basic usage example:
#define i_val float
#include <stc/cvec.h>
int main(void) {
cvec_float vec = cvec_float_init();
cvec_float_push_back(&vec, 10.f);
cvec_float_push_back(&vec, 20.f);
cvec_float_push_back(&vec, 30.f);
c_foreach (i, cvec_float, vec)
printf(" %g", *i.ref);
cvec_float_del(&vec);
}With six different containers:
#include <stdio.h>
#include <stc/ccommon.h>
struct Point { float x, y; };
int Point_compare(const struct Point* a, const struct Point* b) {
int cmp = c_default_compare(&a->x, &b->x);
return cmp ? cmp : c_default_compare(&a->y, &b->y);
}
#define i_key int
#include <stc/cset.h> // cset_int: unordered set
#define i_tag pnt
#define i_val struct Point
#define i_cmp Point_compare
#include <stc/cvec.h> // cvec_pnt: vector of struct Point
#define i_val int
#include <stc/cdeq.h> // cdeq_int: deque of int
#define i_val int
#include <stc/clist.h> // clist_int: singly linked list
#define i_val int
#include <stc/cstack.h>
#define i_key int
#define i_val int
#include <stc/csmap.h> // csmap_int: sorted map int => int
int main(void) {
// define six containers with automatic call of init and del (destruction after scope exit)
c_forauto (cset_int, set)
c_forauto (cvec_pnt, vec)
c_forauto (cdeq_int, deq)
c_forauto (clist_int, lst)
c_forauto (cstack_int, stk)
c_forauto (csmap_int, map)
{
// add some elements to each container
c_emplace(cset_int, set, {10, 20, 30});
c_emplace(cvec_pnt, vec, { {10, 1}, {20, 2}, {30, 3} });
c_emplace(cdeq_int, deq, {10, 20, 30});
c_emplace(clist_int, lst, {10, 20, 30});
c_emplace(cstack_int, stk, {10, 20, 30});
c_emplace(csmap_int, map, { {20, 2}, {10, 1}, {30, 3} });
// add one more element to each container
cset_int_insert(&set, 40);
cvec_pnt_push_back(&vec, (struct Point) {40, 4});
cdeq_int_push_front(&deq, 5);
clist_int_push_front(&lst, 5);
cstack_int_push(&stk, 40);
csmap_int_insert(&map, 40, 4);
// find an element in each container
cset_int_iter_t i1 = cset_int_find(&set, 20);
cvec_pnt_iter_t i2 = cvec_pnt_find(&vec, (struct Point) {20, 2});
cdeq_int_iter_t i3 = cdeq_int_find(&deq, 20);
clist_int_iter_t i4 = clist_int_find(&lst, 20);
csmap_int_iter_t i5 = csmap_int_find(&map, 20);
printf("\nFound: %d, (%g, %g), %d, %d, [%d: %d]\n", *i1.ref, i2.ref->x, i2.ref->y,
*i3.ref, *i4.ref,
i5.ref->first, i5.ref->second);
// erase the elements found
cset_int_erase_at(&set, i1);
cvec_pnt_erase_at(&vec, i2);
cdeq_int_erase_at(&deq, i3);
clist_int_erase_at(&lst, i4);
csmap_int_erase_at(&map, i5);
printf("After erasing elements found:");
printf("\n set:"); c_foreach (i, cset_int, set) printf(" %d", *i.ref);
printf("\n vec:"); c_foreach (i, cvec_pnt, vec) printf(" (%g, %g)", i.ref->x, i.ref->y);
printf("\n deq:"); c_foreach (i, cdeq_int, deq) printf(" %d", *i.ref);
printf("\n lst:"); c_foreach (i, clist_int, lst) printf(" %d", *i.ref);
printf("\n stk:"); c_foreach (i, cstack_int, stk) printf(" %d", *i.ref);
printf("\n map:"); c_foreach (i, csmap_int, map) printf(" [%d: %d]", i.ref->first,
i.ref->second);
}
}Output
Found: 20, (20, 2), 20, 20, [20: 2]
After erasing elements found:
set: 10 30 40
vec: (10, 1) (30, 3) (40, 4)
deq: 5 10 30
lst: 5 10 30
stk: 10 20 30 40
map: [10: 1] [30: 3] [40: 4]
Because it is headers-only, headers can simply be included in your program. The methods are static by default (some inlined). You may add the include folder to the CPATH environment variable to let GCC, Clang, and TinyC locate the headers.
If containers are used across several translation units with common instantiated container types, it is recommended to build as a "library" to minimize the executable size. To enable this mode, specify -DSTC_HEADER as a compiler option in your build environment and place all the instantiations of containers used in a single C-source file, e.g.:
// stc_libs.c
#define STC_IMPLEMENTATION
#include <stc/cstr.h>
#include "Point.h"
#define i_tag ii
#define i_key int
#define i_val int
#include <stc/cmap.h> // cmap_ii: int => int
#define i_tag ix
#define i_key int64_t
#include <stc/cset.h> // cset_ix
#define i_val int
#include <stc/cvec.h> // cvec_int
#define i_tag pnt
#define i_val Point
#include <stc/clist.h> // clist_pntSTC, like c++ STL, has two sets of methods for adding elements to containers. One set begins with emplace, e.g. cvec_X_emplace_back(). This is a convenient alternative to cvec_X_push_back() when dealing non-trivial container elements, e.g. strings, shared pointers or other elements using dynamic memory or shared resources.
The emplace methods constructs or clones the given elements before they are added to the container. In contrast, the non-emplace methods moves the given elements into the container. For containers of integral or trivial element types, emplace and corresponding non-emplace methods are identical.
| non-emplace: Move | emplace: Clone | Container |
|---|---|---|
| insert() | emplace() | cmap, cset, csmap, csset, cvec, cdeq, clist |
| insert_or_assign(), put() | emplace_or_assign() | cmap, csmap |
| push() | emplace() | cstack, cqueue, cpque |
| push_back() | emplace_back() | cvec, cdeq, clist |
| push_front() | emplace_front() | cdeq, clist |
Strings are the most commonly used non-trivial data type. STC containers have proper pre-defined definitions for cstr container elements, so they are fail-safe to use both with the emplace and non-emplace methods:
#define i_val_str // special macro to enable container of cstr
#include <stc/cvec.h> // vector of string (cstr)
...
c_forvar (cvec_str vec = cvec_str_init(), cvec_str_del(&vec)) // defer vector destructor to end of block
c_forvar (cstr s = cstr_lit("a string literal"), cstr_del(&s)) // cstr_lit() for literals; no strlen() usage
{
const char* hello = "Hello";
cvec_str_push_back(&vec, cstr_from(hello); // construct and add string from const char*
cvec_str_push_back(&vec, cstr_clone(s)); // clone and add an existing cstr
cvec_str_emplace_back(&vec, "Yay, literal"); // internally constructs cstr from string-literal
cvec_str_emplace_back(&vec, cstr_clone(s)); // <-- COMPILE ERROR: expects const char*
cvec_str_emplace_back(&vec, s.str); // Ok: const char* input type.
}This is made possible because the type configuration may be given an optional conversion/"rawvalue"-type as template parameter, along with a back and forth conversion methods to the container value type. By default, rawvalue has the same type as value.
Rawvalues are also beneficial for find() and map insertions. The emplace() methods constructs cstr-objects from the rawvalues, but only when required:
cmap_str_emplace(&map, "Hello", "world");
// Two cstr-objects were constructed by emplace
cmap_str_emplace(&map, "Hello", "again");
// No cstr was constructed because "Hello" was already in the map.
cmap_str_emplace_or_assign(&map, "Hello", "there");
// Only cstr_from("there") constructed. "world" was destructed and replaced.
cmap_str_insert(&map, cstr_from("Hello"), cstr_from("you"));
// Two cstr's constructed outside call, but both destructed by insert
// because "Hello" existed. No mem-leak but less efficient.
it = cmap_str_find(&map, "Hello");
// No cstr constructed for lookup, although keys are cstr-type.Apart from strings, maps and sets are normally used with trivial value types. However, the last example on the cmap page demonstrates how to specify a map with non-trivial keys.
| Name | Description | Container |
|---|---|---|
| erase() | key based | csmap, csset, cmap, cset, cstr |
| erase_at() | iterator based | csmap, csset, cmap, cset, cvec, cdeq, clist |
| erase_range() | iterator based | csmap, csset, cvec, cdeq, clist |
| erase_n() | index based | cvec, cdeq, cstr |
| remove() | remove all matching values | clist |
It is possible to forward declare containers. This is useful when a container is part of a struct, but still not expose or include the full implementation / API of the container.
// Header file
#include <stc/forward.h> // only include data structures
forward_cstack(pnt, struct Point); // declare cstack_pnt and cstack_pnt_value_t, cstack_pnt_iter_t;
// the element may be forward declared type as well
typedef struct Dataset {
cstack_pnt vertices;
cstack_pnt colors;
} Dataset;
...
// Implementation
#define F_tag pnt // define F_tag or an empty i_fwd if the container was forward declared.
#define i_val struct Point
#include <stc/cstack.h>
Define either i_prefix or i_tag as empty:
#define i_prefix
#define i_tag ivec
#define i_val int
#include <stc/cvec.h>
ivec vec = ivec_init();
ivec_push_back(&vec, 1);
- cstr, cvec: Type size: 1 pointer. The size and capacity is stored as part of the heap allocation that also holds the vector elements.
- clist: Type size: 1 pointer. Each node allocates a struct which stores the value and next pointer.
- cdeq: Type size: 2 pointers. Otherwise like cvec.
- cmap: Type size: 4 pointers. cmap uses one table of keys+value, and one table of precomputed hash-value/used bucket, which occupies only one byte per bucket. The closed hashing has a default max load factor of 85%, and hash table scales by 1.6x when reaching that.
- csmap: Type size: 1 pointer. csmap manages its own array of tree-nodes for allocation efficiency. Each node uses only two 32-bit ints for child nodes, and one byte for
level. - carr2, carr3: Type size: 1 pointer plus dimension variables. Arrays are allocated as one contiguous block of heap memory, and one allocation for pointers of indices to the array.
- csptr: Type size: 2 pointers, one for the data and one for the reference counter.