AB Iblocks New

//Params:
$iblockA = 44;
$iblockB = 51;
$pregMatchStr = '#\((.*?)\)#';
$testCountElem = 10;
$test = true;
//Script:
CModule::IncludeModule('iblock');
$dbIblockB = CIblockElement::GetList([], ['IBLOCK_ID' => $iblockB], false, false, ['NAME', 'ID', 'XML_ID']);
$arNamesB = [];
$cnt = 0;
while($obB = $dbIblockB->GetNext()){
	$arXmlId = explode('#', $obB['XML_ID']);
	if(count($arXmlId) == 2)
		$arNamesB[$arXmlId[1]] = $obB['XML_ID'];

	if((int)$testCountElem > 0 && $cnt++ > $testCountElem)
		break;
}



$dbIblockA = CIblockElement::GetList([], ['IBLOCK_ID' => $iblockA, 'XML_ID' => array_flip($arNamesB)], false, false, ['NAME', 'ID', 'XML_ID']);

if($test) {
	print_r(['Найдено' => $dbIblockA->SelectedRowsCount(), 'Выбрано' => count($arNamesB)]);
	print_r($arNamesB);
	die();
}

$el = new CIBlockElement;
$cntUpd = 0;
while($obA = $dbIblockA->GetNext()){
	$el->Update($obA['ID'], ['XML_ID' => $arNamesB[$obA['XML_ID']]]);
	$cntUpd++;
}

echo 'Обновлено: ' . $cntUpd;