Updating all the elements of an IBlock (Bitrix). To use in the code console.

bx_update_elements.php

<?
if (CModule::IncludeModule("iblock")) {
  $res = CIBlockElement::GetList(array(), array('IBLOCK_ID'=>23, 'ACTIVE'=>'Y'), false, false, array('NAME', 'ID', 'IBLOCK_ID', 'PROPERTY_FLAT_NUMBER'));
	//$arElement = $res->Fetch();
	//echo '<pre>'; var_dump($arElement); echo '</pre>';
	while($arElement = $res->GetNext()) {	
		preg_match('(\d+)', ($arElement['NAME']), $matches);
		$flatNumber = null;
		if(count($matches) > 0) {
			$flatNumber = intval($matches[0]);
			CIBlockElement::SetPropertyValues($arElement['ID'], $arElement['IBLOCK_ID'], $flatNumber, 'FLAT_NUMBER');
		} else {
			$flatNumber = "!!! Не обновлено";
		}
		echo "{$arElement['NAME']} ({$arElement['ID']}) => {$flatNumber}<br/>";
	}
}