function buildXml( $data, $wrap= ‘xml‘ ){    $str = "<{$wrap}>";    if( is_array( $data ) ){         if( hasIndex( $data ) ){                    foreach( $data as $k=>$v ){                 $str .= buildXml( $v, $k );            }         }else{            foreach( $data as $v ){                foreach( $v as $k1=>$v1 )                  $str .= buildXml( $v1, $k1 );            }         }    }else        $str .= $data;    $str .= "</{$wrap}>";    return $str;}function hasIndex( $arr ){    return array_keys($arr) !== range(0, count($arr) - 1);}$arr1 = [    ‘title‘=>‘title‘,    ‘bbb‘=>[        ‘AAA‘=>12,        ‘BBB‘=>555    ]];$arr2 = [    ‘aaa‘=>1,    ‘bbb‘=>[        [‘AAA‘=>[            ‘BBB‘=>[                [‘DDDD‘=>111],[‘DDDD‘=>222]            ]                ]],        [‘AAA‘=>6]    ]];header("Content-type: text/xml");echo ‘<?xml version="1.0" encoding="utf-8"?>‘;echo buildXml($arr2);