#include <stdio.h>
static int shared = 3;     /* This is the file-scope variable (with 
                            * internal linkage), visible only in 
                            * this compilation unit. 
                            */
extern int overShared = 1; /* This one has external linkage (not
                            * limited to this compilation unit). 
                            */
int overSharedToo = 2;      /* Also external linkage
                            */
static void changeShared(void);
static void localShadow(void);
static void paramShadow(int shared);
int main(void)
{
    printf("%d\n", shared); /* Reference to the file-scope 
                             * variable.
                             */
    changeShared();
    printf("%d\n", shared);

    localShadow();
    printf("%d\n", shared);

    paramShadow(1);
    printf("%d\n", shared);

    return 0;
}

static void changeShared(void)
{
    shared = 5; /* Reference to the file-scope 
                 * variable in a function.
                 */
}
static void localShadow(void)
{
    int shared; /* local variable that will hide 
                 * the global of the same name
                 */
    shared = 1000; /* This will affect only the local variable and will
                    * have no effect on the file-scope variable of the
                    * same name. 
                    */
}
static void paramShadow(int shared)
{
    shared = -shared; /* This will affect only the parameter and will have no
                       * effect on the file-scope variable of the same name. 
                       */
}