修改数组的值和多维数组排序

foreach($ret as $key => $value) {  //将数组元素中为空地补0，且添加sum元素的计算，注意修改数组的值，需要$key定位到是数组的哪一个地方需要修改，而不能简单地修改$value的值，因为$value只是一个临时的变量而已
    $sum = 0;
    if (isset($value['new_amount'])) {
        $sum += $value['new_amount']; 
    } else {
        //$value['new_amount'] = 0; 
        //$value['new_amount'] = 0;
        $ret[$key]['new_amount'] = 0;
        $ret[$key]['new_amount'] = 0;
    }
    if (isset($value['level_10_amount'])) {
        $sum += $value['level_10_amount'];
    } else {
        //$value['level_10_amount'] = 0;
        //$value['level_10_amount'] = 0;
        $ret[$key]['level_10_amount'] = 0;
        $ret[$key]['level_10_amount'] = 0;
    }
    if (isset($value['continus_login_amount'])) {
        $sum += $value['continus_login_amount'];
    } else {
        //$value['continus_login_amount'] = 0;
        //$value['continus_login_amount'] = 0;
        $ret[$key]['continus_login_amount'] = 0;
        $ret[$key]['continus_login_amount'] = 0;
    }
    if ($sum % 10 != 0) {
        $sum = $sum + (10 - $sum % 10);
    }
    //$value['sum'] = $sum;
    $ret[$key]['sum'] = $sum;
}

uasort($ret, 'my_sort'); //按元素sum进行排序
function my_sort($a, $b) { //排序
    if ($a['sum'] == $b['sum']) return 0;
    return ($a['sum'] > $b['sum']) ? -1 : 1; //这里可以决定是倒序排，还是正序排
}

 

数组按照键id的值进行升序排序

<?php 
$array[] = array('id'=>1,'price'=>50);
$array[] = array('id'=>2,'price'=>70);
$array[] = array('id'=>3,'price'=>30);
$array[] = array('id'=>4,'price'=>20);
foreach ($array as $key=>$value){
  $id[$key] = $value['id'];
  $price[$key] = $value['price'];
}
array_multisort($price,SORT_NUMERIC,SORT_DESC,$id,SORT_STRING,SORT_ASC,$array);
?>