#include<stdio.h>
 
int counter = 0;   /* global because we are outside
        all blocks.   */
int func(void);
 
main()
{
 counter++;    /* global because it has not been
        declared within this block */
 printf("counter is %2d before the call to func\n", counter); 
 
 func();     /* call a function.  */
 
 printf("counter is %2d after the call to func\n", counter); 
}
 
int func(void)
{
 int counter = 10;   /* local.   */
 printf("counter is %2d within func\n", counter); 
}