Using a stream function into another module

Hello, I want to use two stream functions (stream_array_to_fd_set and stream_array_from_fd_set) in a module (/etc/modulename/modulename.c). To use them, i included the streamsfuncs.h file, with: #include "ext/standard/streamsfuncs.h" The problem is that when I want to compile, i've these errors: /home/samuel/Développement/workspaces/C-Cpp/PHP_5_3/ext/sockets/sockets.c:877: undefined reference to `stream_array_to_fd_set' /home/samuel/Développement/workspaces/C-Cpp/PHP_5_3/ext/sockets/sockets.c:884: undefined reference to `stream_array_to_fd_set' /home/samuel/Développement/workspaces/C-Cpp/PHP_5_3/ext/sockets/sockets.c:891: undefined reference to `stream_array_to_fd_set' /home/samuel/Développement/workspaces/C-Cpp/PHP_5_3/ext/sockets/sockets.c:936: undefined reference to `stream_array_emulate_read_fd_set' /home/samuel/Développement/workspaces/C-Cpp/PHP_5_3/ext/sockets/sockets.c:957: undefined reference to `stream_array_from_fd_set' /home/samuel/Développement/workspaces/C-Cpp/PHP_5_3/ext/sockets/sockets.c:958: undefined reference to `stream_array_from_fd_set' /home/samuel/Développement/workspaces/C-Cpp/PHP_5_3/ext/sockets/sockets.c:959: undefined reference to `stream_array_from_fd_set' How can I do to use them into my module ? Regards, Samuel ROZE.