function test1_static () {
  static $num = 0;
  $num++;
  echo 'test1_static(): ' . $num;
}
function test2 () {
  $num++;
  echo  'test2(): ' . $num;
}
test1_static(); // test1_static(): 1
test1_static(); // test1_static(): 2
test2 (); // test2(): 1
test2 (); // test2(): 1