C Language Modularity:Using “static” data and functions

/* This illustrates the use of the “static” keyword

* to prevent local module data structures and

* functions from being visible outside this file.

*/

static int x; /* data global to this file only */

/* A global function to initialize the hidden

* data structure from outside the module:

*/

void

initialize(int j){

x = j;

}

/* A global function to return the value of

* the hidden data structure in the module:

*/

int

fetch(){

return local_func(x);

}

/* A local function, invisible outside this file,

* to perform support operations in the module:

*/

static int

local_func(int j){

return j * 2;

}