<?php
session_start();
if($_POST){
$_SESSION['old']=array('one','two','three','four','five');
$_SESSION['old']=array();
$_SESSION['old']=array('two','five');
$new=(array) $_POST['big'];
foreach($new as $k=>$v){
if(!in_array($v,$_SESSION['old'])){
$_SESSION['old'][]=$v;
echo 'add '.$v;
echo '<br />';
}else{
echo 'mod '.$v;
echo '<br />';
}
}
foreach($_SESSION['old'] as $k=>$v){
if(!in_array($v,$new)){
$id=array_keys($_SESSION['old'],$v);
unset($_SESSION['old'][$id[0]]);
echo 'del '.$v;
echo '<br />';
}
}
echo "<pre>";
print_r($_SESSION['old']);
}
?>
<form method="post">
<input type="checkbox" name="big[]" value="one" /> one<br />
<input type="checkbox" name="big[]" value="two" /> two<br />
<input type="checkbox" name="big[]" value="three" /> three<br />
<input type="checkbox" name="big[]" value="four" /> four<br />
<input type="checkbox" name="big[]" value="five" /> five<br />
<input type="submit" value="submit" name='abc'>
</form>
