use warnings;

#use Inline C => Config =>
#    BUILD_NOISY => 1;

use Inline C => <<'EOC';

static int x = 5;

void set_x(int z) {
   x = z;
}

void get_x(char * id) {
   printf("%s %d\n", id, x);
}

EOC

get_x('1st call:');

if($pid = fork()) {
  waitpid($pid,0);
} else {
  set_x(10);
  get_x('2nd call:');
  exit(0);
}
 
get_x('3rd call:');
##</code><code>##

1st call: 5
2nd call: 10
3rd call: 5

##</code><code>##

1st call: 5
2nd call: 10
3rd call: 10

##</code><code>##

use warnings;

$g = 5;
print "1st call: $g\n";

if($pid = fork()) {
  waitpid($pid,0);
} else {
  $g = 10;
  print "2nd call: $g\n";
  exit(0);
}

print "3rd call: $g\n";

##</code><code>##

1st call: 5
2nd call: 10
3rd call: 5