double parentheses

[samsplug]

below is an extract of code which i have copied from a book which i have been studying...
The code is a segment from a script about paginating query results. I understand almost all of the below code except the ... (($display * ($i – 1))) ... Why is a double parentheses used around the $display variable.

For ($i = 1; $i <= $pages; $i++) {
	if ($i != $current_page) {
		echo ‘< a href=”view_users.php?s=’ . (($display * ($i – 1))) . ‘&p=’ . 
                $pages . ‘”>’ . $i . ‘</a> ‘;
	} else {
		echo $i . ‘ ‘;
	}
}

I'd be really grateful if someone could explain that to me 🙂
thanks

[dagon]

typo, mistake, personal preference, it makes no difference to the code.

[jaql]

Yeah, there's really no reason to do that. This should work just fine as well:

<?php
for ($i = 1; $i <= $pages; $i++) {
   if ($i != $current_page) {
      echo '<a href="view_users.php?s='.($display*($i – 1)).'&p='.$pages.'">'.$i.'</a>';
   }
   else {
      echo $i;
   }
}

[nrg_alpha]

Given the BEDMAS (Brackets, Exponents, Division, Muliplication, Addition, Subtraction) order of operations in mathematics, the end result in this case is the same, be it

(($display ($i – 1))) or ($display($i – 1)), as $i will be subtracted by 1 first, then multiplied by $display afterwards.

[dagon]

I'm sure some one can come up with more flogging of this dead horse, oh i know its probably slower by a few nano seconds with those extra brackets😃