Variables

[S.Lange]

 I am trying to write a set of functions and procedures in C which will be used 
as a set of library routines. But I can not find any way to make the variables
used inside these routines unavailable to the applications program.
The problem is hiding certain functions, procedures and variables from the
application program, but a few functions and procedures must be accessible
from the main program.
Ideally I would like to include the routines as a  #include .

               CAN ANYONE HELP PLEASE


                         THANX