global, static variables in C

In this post, I am going to explain the global, static variables in C

********
main.c
********
int a[2];             // this is the non-static global variable, could be used at other files
int static b;        // this is the static global variable, could only be used in this file

void main()
{
 int static c;       // this is the static variable like in java. associated with class.
                          // it only has one copy,
 swap();
}

********
swap.c
********
extern int a[2];

void swap()
{
int tmp;
tmp = a[0];
a[0] = a[1];
a[1] = a[0]
}

deals please see slides 14
http://www.cs.gmu.edu/~setia/cs367/slides/index.html