public function indexOf( AbstractElement $element ) {
		$search_result = array_search($element, $this->childElements, true);

		return $search_result === false ? null : $search_result;
	}
public function indexOf( AbstractElement $element ) {
		$search_result = array_search($element, $this->childElements, true);

		return $search_result === false ? null : $search_result;
	}
public function indexOf ( AbstractElement $ element ) { $ search_result = array_search ( $ element , $ this -> childElements , true ) ; return $ search_result === false ? null : $ search_result ; }
Get the index of a child element or null if not found.

@param AbstractElement $element
@return int|null
Get the index of a child element or null if not found .