PHP函数 explode和eval的使用

<?php
header('Content-Type: text/html; charset=utf-8');
define ('ROOT', $_SERVER['DOCUMENT_ROOT']);
include ROOT.'/assets/php/head.php';

/**
 * explode() 函数把字符串打散为数组。
 * eval() 函数把字符串按照 PHP 代码来计算。
 * */

$val='60 50+80 06+40*30';
$bool = true;
$type = '';

mill($val);

//磨粉机
function mill($val){
    $vals = explode(' ',$val);
    print_r($vals);

    $a = evev($vals[0]);
    echo '<br>'.$vals[0].'=';
    echo $a;
   
    $b = evev($vals[1]);
    echo '<br>'.$vals[1].'=';
    echo $b;

    $c = evev($vals[2]);
    echo '<br>'.$vals[2].'=';
    echo $c;
}

function evev($num){
    $result = eval("return $num;");
    return $result;
}
?>
<?php include ROOT.'/assets/php/foot.php';
//查改样式
$chck = array();
chck($chck);
?>

Array ( [0] => 60 [1] => 50+80 [2] => 06+40*30 )
60=60
50+80=130
06+40*30=1206