Open source free C/C++ library work sharing

1. boost  - Provides a repository of peer-reviewed portable C++ source libraries for free. The emphasis is on libraries that work well with the C++ standard library.
2. STLport (STL Library):
   This version of STL (C++ Standard Template Library) is available for free from their website. It also apparently ships with a current version of the Borland C++ compiler.
3. ACDK - Artefaktur Component Development Kit  - Platform independent C++ component framework similar to Java or .NET (reflection, threading, Unicode, garbage collection, io, net, util, XML, etc.) Integrated Java, Perl, Python, Tcl, Lisp, COM and CORBA. [Open source free c++ library classes]
4. Libcwd  - A well-documented, thread-safe library that enables C++ developers to debug their applications. It includes support for ostream-based debug output from custom debug channels, memory allocation debugging, and runtime support such as printing the file location and teardown name of source template arguments. [free c++ library classes]
5. Generic C++  - Framework for Threads, Sockets, File Access, Deamons, Persistence, and Clear Systems, Services. [Open source free c++ library classes]
6. Database Template Library  - Provides ODBC recordsets as STL containers, including writing content back to the database.
7. Generic Text Transformation Library  - C++ classes and libraries of STL strings to parse and modify. CTTL substring classes can be compared, inserted, replaced, and parsed using EBNF grammars. The compiled program implements a recursive-descent LL(INF) parser. [Open source free c++ library class]
8. SGI Standard Template Library (STL):
   If your compiler does not have an up-to-date implementation of the Standard Template Library, you may wish to consider this version freely available from SGI.
9. AccessLog  - A C++ wrapper for the Berkeley Database library in XBase fashion.
10. Audio/Video 3D C++ Programming Library  - AV3D for C++ is a multi-platform high-performance programming library. Main features: 3D graphics, sound support (SB, and S3M), controller interface (keyboard, mouse, and joystick), XMS.
11. Babylon Library  - A collection of simple routines and classes that can be used as building blocks for larger projects. Many methods are portable and tuned for embedded systems. [Open source free c++ library classes]
12. Open EzBasic  - A C++ based library that can be used to make programs in VB using functions. The library has 25 classes including GUI, Thread, String, Active-X. An easy way to convert VB code to C++. [Open source free c++ library classes]
13. dlib C++ library  - collection of various classes. Sockets, threads, GUI and directory browsing interfaces. There are also many container classes and other miscellaneous things like a large integer. [Open source free c++ library classes]
14. The BitMagic-C++ class implements library compression of bit vectors using several types of dynamic adaptation. Can be used in databases and search systems. [Open source free c++ library class]
15. freeodbc++  - A C++ library for accessing SQL databases. Designed with standards in mind, it provides a subset of the well-known JDBC 2.0 and runs on top of ODBC. [Open Source, LGPL]
16. Crypto++  - Free C++ library of cryptographic schemes: including ciphers, message authentication codes, one-way hash functions, public-key cryptography, and key protocol schemes.
17. Easy Win 32  - Makes Windows programming easier when using the Windows API. [Open source free c++ library class].
18. Simple XML Persistence Library - Lightweight C++ library for object serialization in XML.
19. SOL++2000  - Free C++ class library for Microsoft Windows. All source files of the library and many example programs are available.
20. Standard J2K Library  - A fully portable C++ library that provides a standard set of classes similar to the Java Common API. [Open Source, LGPL]
21. GNU Nana  - Library of many tested, proven methods to improve C and C++ code. Includes: Extended Logging, Assertion Checking, Designer Contracts: DbC. Supports real-time measurement, performance statistics for code snippets, and tracking of program execution codex without modification.
22. libunicows:
    libunicows allows you to write programs that use Unicode on Windows 9x/ME, using a compiler other than Microsoft Visual C++ (Visual C++ is required for the Microsoft Unicows library). The library supports (at the time I write this) MinGW, Visual C++ 6, Borland C++ and Watcom (and OpenWatcom) C/C++.
23. OSLib:
    OSLib is a C library for programmers to write system software (whether it's embedded software or even an entire operating system kernel). It contains 4 libraries (extender library, standard C library, math library and kernel library).
24. MIT Exo-OS:
    The MIT Exo-OS attempts to provide a level of abstraction to the hardware so that you can focus on other aspects of implementing the OS. Might be useful to those who intend to write OS.
25. OSKit Project (Flux):
    The OSKit Project is a 34-component C framework that provides a wide variety of facilities, useful to those planning to write operational system kernels, servers, bootloaders, embedded applications and the like.
26. Regex:
    Regex is a regular expression parser, released to the public domain (or so the website says). This is useful if you want to write a program using regular expressions, but don't want to use GPL expressions from the Free Software Foundation. (The package is in the middle of the page you link to; just scroll down to find it.
27. txObject ATK  - A collection of platform-independent C++ class libraries, providing five layers including object libraries, IO and timers, threads, inter-process framework communication and distributed object communication.
28. libsigc++ callback framework for C++:
    libsigc++ has C++ classes that give you a type-safe callback system. You can define signals and assign callback functions to these signals.
29. Standard Function Library:
    The Standard Function Library (SFL) contains routines for compression, encryption, encoding, data type conversion, data output formatting, process control, date, time, calendar, symbol table, linked list, configuration files, error messages File, string operations.
30. Virtual X Class Library (VXCL)  - A powerful collection of C++ classes. [Open Source, LGPL]
31. Views - C++ Standard Template Library Extension:
    Views extend the STL to include domain views, which allows you to simplify your code when using containers.
32. VXL (Vision-something-Libraries) -  A collection of C++ libraries designed for computer vision research. Includes Mapping, Geometry, Numbers, Streaming I/O, Basic Templates, Persis. VXL is written in ANSI/ISO C++ and designed to be portable on many platforms.
33. Wildebeest Lightning:
    GNU Lightning is a library of routines that allow programs to generate run-time assembly language code. It abstracts the target CPU, exposing your program to a standardized RISC instruction set.
34. GetPot:
    GetPot is an anagram of the ubiquitous getopt, allowing programs to parse command lines and simple input files, simply by including header files (the entire library is obviously in the header files).
35. ZThreads  - An advanced object-oriented, cross-platform C++ threading and synchronization library. [GPL]
36. CImg Library  - The C++ templated image processing library providing simple classes and functions for processing and displaying images. Available for Unix/X11 and Windows. [open source, GPL]
37. MyLibC:
    MyLibC is a clone of glibc for Windows. The author wrote this article to reduce the executable size when using glib on Windows. Source provided.
38. IO95: Win95 LFN API Wrapper Library:
    This library has functions you can call from MSDOS programs to access the Long File Name (LFN) API in Windows 95 and later.
39. U2NT Library: Unix/NT Cross-Platform Library:
    This is a library that simplifies the work required to port Unix programs to NT. There aren't many details on the library's features on the website, but you can just download it from their website and check it out yourself.
40. ClibPDF PDF library:
    ClibPDF is a C library that allows you to create PDFs from your applications or even CGI scripts.
41. CxImage  - Win32 platform C++ class for loading, saving, displaying, converting BMP, JPEG, GIF, PNG, TIFF, MNG and ICO images.
42. Overall:
    Ensemble is a toolkit for building reliable distributed applications. This toolkit contains a protocol library that can be used to build distributed applications. The library primarily uses UDP/IP sockets.
43. GLT  - C++ programming library for interactive 3D graphics using OpenGL. Designed to enhance the OpenGL API with convenient mechanisms for manipulating the OpenGL state machine.
44. Dislin:
    This is a plotting library for displaying data as curves, bar charts, pie charts, 3D colormaps, surfaces, contours, and maps.
45. OpenTurn  - C++ library to help build autonomous character turning behaviors in games and animations
46. LibSMI:
    This C library "allows network management applications to access SMI MIB module information through a well-defined API that hides the nasty details of finding and parsing SMIv1/v2 MIB modules.
47. TIFF Tools  - A set of C++ bindings to libtiff and some utilities to process multipage TIFF files created from scanned documents. [Open Source, GPL]
48. Visualization Toolkit (VTK) - C++ library for 3D computer graphics, image processing, and visualization. There are also implementation class libraries based on Tcl, Python and Java.
49. GNET  Network Library:
    This is a simple network library built on top of glib. It is available for Linux, BSD, Mac OS X, Solaris, HP and Windows.
50. Whisper C++ Application Framework:
    Whisper is a general-purpose C++ application framework that takes advantage of templates, multiple inheritance, STL, and exceptions. It is portable to Macintosh and Win32. It contains many debugging tools.
51. GNU Common C++ :
    GNU Common C++ is a C++ framework for developing portable threaded applications. It is released under the GNU GPL license.
52. OPP C++ Class Library: A
    C++ class library with many functions (including classes) for retrieving files via HTTP, sending and receiving emails, database classes, threading support, string classes, HTML parser, etc. It supports Unix platforms.
53. MySQL++  - A C++ API for MySQL. Try to make using queries like using other STL containers.
54. Boehm-Demers-Weiser (English: Boehm-Demers-Weiser)  Garbage Collector:
    A garbage collector for C/C++ that can also be used as a memory leak detector. You can simply replace calls to malloc() with GC_malloc(). Support Win32, Win32s, OS/2, MacOS, AmigaDOS and Unix systems.
55. S-mail project - DObject library C++ database connection - C++ database interface similar to JDBC technology. Currently available drivers support: MySQL database, mdb file via ADO component (win32 platform only). [Open Source, GPL]