php 二维数组排序

$a=array(
    array("key1"=>940,"key2"=>"blash"),
    array("key1"=>23,"key2"=>"this"),
    array("key1"=>894,"key2"=>"that")
);

function asc_number($x,$y){
    if($x["key1"]>$y["key1"]){
        return true;
    }elseif($x["key1"]<$y["key1"]){
        return false;
    }else{
        return 0;
    }
}
//strcasecmp   不区分大小写
//strcmp          区分大小写
function string_sort($x,$y){
    return strcasecmp($x["key2"], $y["key2"]);
}
//数组过滤
$var=300;
$int_options = array("options"=>
array("min_range"=>0, "max_range"=>256));
var_dump(filter_var($var, FILTER_VALIDATE_INT, $int_options));