What's qLibc? [](https://github.com/wolkykim/qlibc/actions)

April 19, 2026 · View on GitHub

qLibc is currently one of the most functionally-complete, publicly-licensed C/C++ libraries. The goal of the qLibc project is to provide a simple and powerful general purpose C/C++ library that includes all kinds of containers and general library routines. It provides a ready-made set of common container APIs with a consistent API look.

qLibc Copyright

qLibc is published under the 2-clause BSD license, also known as the Simplified BSD License. Please refer to the LICENSE document included in the package for more details.

API Reference

qlibc Core API Reference
- Containers for Key/Value pairs
  - Tree Table --- in binary tree (left-leaning red-black tree) data structure.
  - Hash Table --- in hash-based data structure.
  - Static Hash Table --- in fixed size memory(array/mmapped/shared).
  - List Table --- in (doubly) linked-list data structure.
- Containers for Objects
  - List --- Doubly Linked List.
  - Vector --- implements a growable array of elements.
  - Queue --- FIFO(First In First Out) implementation.
  - Stack --- LIFO(Last In First Out) implementation.
- General utilities.
  - String --- string trimmer, modifier, replacer, case converter, pattern detectors, ...
  - I/O --- non-blocking I/O, stream reader/writer, ...
  - File --- file locking, file/directory handler, path correctors, ...
  - IPC, semaphores, shared memory
  - Encoders/decoders --- URL encoder/decoder, Base64 encoder/decoder, Hex encoder/decoder, ...
  - Hashes --- Murmur hashes, FNV hashes, MD5 hashes, ...
  - Time --- time diff, time format conversion, ...
qLibc Extension API Reference
- Apache-style Configuration File Parser.
- INI-style Configuration File Parser.
- HTTP client.
- Rotating File Logger.
- Database (MySQL) interface.
- Token-Bucket

qLibc Tables at a Glance

Characteristics	Tree Table	Hash Table	Static Hash Table	List Table
Data structure	Binary Tree	Slot Index	Block Array	Linked-List
Search complexity	O(log n)	O(1) / O(n)	O(1) / O(n)	O(n)
Insert complexity	O(log n)	O(1) / O(n)	O(1) / O(n)	O(1)
Delete complexity	O(log n)	O(1) / O(n)	O(1) / O(n)	O(n)
Space complexity	O(n)	O(n)	-	O(n)
Space allocation	Dynamic	Dynamic	Pre-allocation	Dynamic
Key Stored Sorted	Yes	No	No	Yes (option)
User comparator	Supported	-	-	Supported
Duplicated keys	No	No	No	Yes (option)
Key stored digested	No	No	Yes	No
Search Nearest Key	Yes	No	No	No
Iterator support	Yes	Yes	Yes	Yes
Iterator visit order	min -> max	random	random	insert order
Thread-safe option	Supported	Supported	User	Supported
Can use shared mem	No	No	Yes	No

Consistent API Look

All container APIs have a consistent look and feel. It basically provides a creator function which usually returns a pointer to a container structure. Also, all functions related to the container can be accessed through function pointers inside the container or through traditional direct-access APIs.

So, regardless of which container you use, you can simply put elements into a list with container->put(container, ...) or you can call them using direct APIs such as qtreetbl_put(container, ...).

The example below illustrates what it looks like.

  // create a hash-table.
  qhashtbl_t *tbl = qhashtbl(0, QHASHTBL_THREADSAFE);
  
  // add an element whose key is "score".
  int x = 12345;
  tbl->put(tbl, "score", &x, sizeof(int));
  
  // get the value of the element.
  int *px = tbl->get(tbl, "score", NULL, true);
  if(px != NULL) {
    printf("%d\n", *px);
    free(px);
  }
  
  // release table
  tbl->free(tbl);

Here is an identical implementation with a Linked-List-Table container. You may notice that there aren't any code changes at all, except for 1 line in the table creation. This is why qLibc encapsulates corresponding function pointers inside the container object.

  // create a linked-list-table. THE ONLY LINE YOU NEED TO CHANGE.
  qlisttbl_t *tbl = qlisttbl(QLISTTBL_THREADSAFE);
  
  // add an element whose key is "score".
  int x = 12345;
  tbl->put(tbl, "score", &x, sizeof(int));
  
  // get the value of the element.
  int *px = tbl->get(tbl, "score", NULL, true);
  if(px != NULL) {
    printf("%d\n", *px);             
    free(px);
  }
  
  // release table
  tbl->free(tbl);

Looking for people to work with.

We're looking for people who want to work together to develop and improve qLibc. Currently, we have high demand in the following areas.

Automated testing
Documentation.
New feature implementation.

Contributors

The following people have helped with suggestions, ideas, code or fixing bugs: (in alphabetical order by first name)

If we have forgotten or misspelled your name, please let us know.