Storage Class and Scope Example

/* scope_main.c */
/* external functions and variables */
extern void help();
extern long h_1;

/* Global variables */
int g_1;		/* Uninitialized: default to 0 */

void help_routine()
{
    /* local variable, uninitialized: defaults to undefined */
    int h_1;    	/* Superceeds the declaration of the global h_1 */

    h_1 = 10;
    printf("We are in the help routine h_1 = %d.\n", 10);
}

int main()
{
    printf("Initial g_1 is %ld\n", g_1);
    printf("Initial h_1 is %ld\n", h_1);
    help_routine();
    printf("We are in main and h_1 shouldn't have changed %ld\n", h_1);

    help();
    help();
    help();

    return(0);

}

/* scope_help.c */

/* Global variables */
long h_1 = 5;		/* Pre initialized */
static long h_2 = 40;

static void help_routine()
{
    /* static locals are REALLY global! */
    static long h_2;	/* Superceeds the declaration of the global h_2 */

    h_2++;
    printf("local static h_2 is now %ld\n", h_2);
}

void help()
{
    h_2++;
    printf("global static h_2 is now %ld\n", h_2);
    help_routine();
}

Output
Initial g_1 is 0
Initial h_1 is 5
We are in the help routine h_1 = 10.
We are in main and h_1 shouldn't have changed 5
global static h_2 is now 41
local static h_2 is now 1
global static h_2 is now 42
local static h_2 is now 2
global static h_2 is now 43
local static h_2 is now 3