PHP method to get the index value of the array item with the largest key value in the array

One 、 The problem background

Get the key value of the array item with the largest value from the given array . Uses such as ： Get the name of the student with the highest score in the class .

Two 、 Solution

<?php
/* * created on 2022-qipa-250 * created by www.qipa250.com */
 $arr=array('tom'=>9,'jack'=>3,'kim'=>5,'hack'=>4);
 asort($arr);
 //print_r($arr);
 // Output ：array ( [jack] => 3 [hack] => 4 [kim] => 5 [tom] => 9 )
 $rel=array();
 foreach($arr as $k=>$v){
    
 $rel[]=$k;
 }
 //echo $rel[0];// Output min ：jack
 echo end($rel);// Output Max ：tom
?>