php ldap检索dn的值

I'm trying below code to get the value as ou=grp1 from

dn: uid=john,ou=grp1,ou=people,dc=site,dc=com , but not understanding how to retrieve.

here is the code:

<?php

function pairstr2Arr ($str, $separator='=', $delim=',') {
    $elems = explode($delim, $str);
    foreach( $elems as $elem => $val ) {
        $val = trim($val);
        $nameVal[] = explode($separator, $val);
        $arr[trim(strtolower($nameVal[$elem][0]))] = trim($nameVal[$elem][1]);
    }
        return $arr;
}

//  Example usage:
$string = 'uid=john,ou=grp1,ou=people,dc=site,dc=com';
$array = pairstr2Arr($string);

echo '<pre>';
print_r($array);
echo '</pre>';

?>

output:

<pre>Array
(
    [uid] => john
    [ou] => people //here I want to get output ou=grp1,how?
    [dc] => com
)
</pre>

find output here: https://ideone.com/rE6eaH

Because of ou and dc might have multiple values, you should store those values in array. Thanks to that you can have easy access to data. Check out this code:

<?php

function pairstr2Arr ($str, $separator='=', $delim=',') {
    $elems = explode($delim, $str);

    $arr = array();
    foreach( $elems as $elem => $val ) {
        $val = trim($val);
        $tempArray = explode($separator, $val);

        if(!isset($arr[trim($tempArray[0])]))
            $arr[trim($tempArray[0])] = '';

        $arr[trim($tempArray[0])] .= $tempArray[1].';'; 
    }

    foreach($arr as $key => $value)
    {
        $explodedValue = explode(';', $value);
        if(count($explodedValue) > 2)
        {
            $arr[$key] = $explodedValue;
            unset($arr[$key][count($explodedValue) - 1]);
        }
        else
            $arr[$key] = substr($arr[$key], 0, -1);
    }
    return $arr;
}

//  Example usage:
$string = 'uid=john,ou=grp1,ou=people,dc=site,dc=com';
$array = pairstr2Arr($string);

echo '<pre>';
print_r($array);
echo '</pre>';

?>

Result is:

Array
(
    [uid] => john
    [ou] => Array
        (
            [0] => grp1
            [1] => people
        )

    [dc] => Array
        (
            [0] => site
            [1] => com
        )
)