PHP数组比较问题

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

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？

回复讨论(解决方案)

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

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