array to xml

index.php

<?php

$xml = [
    "payments" => [
        [
            "amount" => "100",
            "initials" => "ih"
        ],
        [
            "amount" => "1000",
            "initials" => "ip"
        ],
    ]    
];

function arrayToXML($xml)
{
    $result = "";
    foreach($xml as $key => $val)
    {
        if (is_array($val))
        {
            if (is_numeric($key))
            {
                $result .= "<item>" . arrayToXML($val) . "</item>";   
            }
            else
            {
                $result .= "<$key>" . arrayToXML($val) . "</$key>";   
            }
        }
        else
        {
            $result .= "<$key>" . $val . "</$key>";
        }
    }
    
    return $result;
}

echo arrayToXML($xml);