php 7的验证eval（）

Question

The original code is this:

$hash_stack = array();
foreach ($values as $key => $val)
{
     array_push($hash_stack, $val['tag']);              
     eval("\$ret[" . implode($hash_stack, "][") . "] = '{$val[value]}';");
     array_pop($hash_stack);
}

It works in php5 but not in php7:

I got this error for each item in array:

Notice: Undefined index: . resultObj][result . in /srv/users/...

I tried to fix it with this:

$value = $val['value'];
$implode = implode($hash_stack, "][");
eval("\$ret[" . $implode . "] = '{$value}';");
array_pop($hash_stack);

But it's still getting an error. What am I doing wrong?

I get this error:

Notice: Use of undefined constant resultObj - assumed 'resultObj' in /srv/use

Answer 1

You're getting that error because your array keys are plain code rather than strings. You'd have to escape and quote them, but... honestly, I'd get rid of the eval altogether.

You should be able to do the same thing with a reference:

$hash_stack = array();
foreach ($values as $key => $val)
{
    array_push($hash_stack, $val['tag']);

    $r = &$ret;
    foreach ($hash_stack as $h)
    {
        $r = &$r[$h];
    }
    $r = $val['value'];

    array_pop($hash_stack);
}