Editing C file input/output (section)

===Extensions{{anchor|POSIX}}===
The [[POSIX]] standard defines several extensions to {{mono|stdio}} in its Base Definitions, among which are a {{mono|readline}} function that allocates memory, the {{mono|fileno}} and {{mono|fdopen}} functions that establish the link between {{mono|FILE}} objects and [[file descriptor]]s, and a group of functions for creating {{mono|FILE}} objects that refer to in-memory buffers.<ref>{{man|bd|stdio.h|SUS}}</ref>