check copy on write of PHP

gistfile1.aw

<?php

$GLOBALS['memstart'] = memory_get_usage();

function mem() {
  $m2 = memory_get_usage();
  echo $m2 - $GLOBALS['memstart'] ."\n";
}
class Foo {
  public function bar($x = null){
    echo "---------start Foo->bar() ----------\n";
    $c = $x;
    mem();
    $c[1] = 21;
    mem();
  }
}

function func($x=null) {
  echo "---------start foo func----------\n";
  $c = $x;
  mem();
  $c[1] = 21;
  mem();
}


$a = range(1,100);
$b = $a;
#$b[1] = 111;
func($a);

$foo = new Foo();
$foo->bar($a);

echo "------- end this script -----------\n";
mem();
echo "\n\n";

/*
RESULT

---------start foo func----------
15176
25200
---------start Foo->bar() ----------
15528
25552
------- end this script -----------
15528

*/
?>