Why Is libxc needed?
There doesn't exist a library for ANSI C99 for common data containers, such as vectors, trees, etc. There also also doesn't exist a library for common functionality, such as error reporting/logging, string functions, configuration management (reading config files), etc...
The programmer working in C doesn't have anything analogous to the Boost C++ library. The extended C library is intended to make some headway into providing this functionality. To ensure...
Cross-platform C++ libraries with a network/internet focus.
NOTE: Current source code as well as bugs/patches are on GitHub:
https://github.com/pocoproject/poco/
C++ class libraries for network-centric, portable applications, integrated perfectly with the C++ Standard Library. Includes network protocols (Sockets, HTTP, FTP, SMTP, POP3, etc.), SQL database access and XML parsing. Licensed under Boost license.