Study of external storage class.

#include <stdio.h>

void add5(void);
void sub3(void);
void show(void);

int main(void)
{
extern int i;

printf( "\n1. main i = %d", i );
add5();
sub3();
show();
printf( "\n2. main i = %d", i );

return 0;
}

void add5(void)
{
extern int i;
/* int i; */

i+=5;
printf( "\nadd5 i = %d", i );
}

void sub3(void)
{
extern int i;
i-=3;
printf( "\nsub3 i = %d", i );
}

void show(void)
{
extern int i;
printf( "\nshow i = %d", i );
}

int i = 5; /* external storage class variable */