php 多维数组排序

//定义一个学生数组

$students = array(
256=>array('name'=>'jon','grade'=>98.5),
2=>array('name'=>'vance','grade'=>85.1),
9=>array('name'=>'stephen','grade'=>94.0),
364=>array('name'=>'steve','grade'=>85.1),
68=>array('name'=>'rob','grade'=>74.6),
);

//按照名称进行排序
function name_sort($x, $y)
{
return strcasecmp($x['name'],$y['name']);
}

//按照成绩进行排序
function grade_sort($x,$y)
{
return ($x['grade'] > $y['grade']);
}

//应用
uasort($students, name_sort);

uasort($students, grade_sort);