PHP数组比较有关问题

PHP数组比较问题

<br />$ar1=array(array('id'=>1,"name"=>"张1","sign"=>""),array('id'=>2,"name"=>"张2","sign"=>""),array('id'=>5,"name"=>"张5","sign"=>""));<br />        $ar2=array(array('id'=>1,"name"=>"张1"),array('id'=>2,"name"=>"张2"));<br />

如果ar2的id与ar1的id相同，那么ar1的sign则复制给1，否则不赋值，怎么解决？
------解决思路----------------------

$ar1=array(array('id'=>1,"name"=>"张1","sign"=>""),array('id'=>2,"name"=>"张2","sign"=>""),array('id'=>5,"name"=>"张5","sign"=>""));<br />$ar2=array(array('id'=>1,"name"=>"张1"),array('id'=>2,"name"=>"张2"));<br /><br />//先将 $ar2 规格化一下<br />foreach($ar2 as $v) $r[$v['id']] = $v;<br />$ar2 = $r;<br /><br />//接下来就简单了<br />foreach($ar1 as &$v) {<br />  if(isset($ar2[$v['id']])) $v['sign'] = 1;<br />}<br /><br />print_r($ar1);<br />

Array<br />(<br />    [0] => Array<br />        (<br />            [id] => 1<br />            [name] => 张1<br />            [sign] => 1<br />        )<br /><br />    [1] => Array<br />        (<br />            [id] => 2<br />            [name] => 张2<br />            [sign] => 1<br />        )<br /><br />    [2] => Array<br />        (<br />            [id] => 5<br />            [name] => 张5<br />            [sign] => <br />        )<br /><br />)<br /><br />