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

[SilveR316]

There is no reason for it.

 

You can remove the parentheses and it will function just the same. Just don't remove the ones from around $i-1.

 

I guess its the author's personal coding style preference. Possibly to make it easier to read.

[samsplug]

There is no reason for it.

 

You can remove the parentheses and it will function just the same. Just don't remove the ones from around $i-1.

 

I guess its the author's personal coding style preference. Possibly to make it easier to read.

Thats weird... They have no purpose at all??

Thanks for the quick reply

[SilveR316]

None whatsoever. You can nest it in 15 parentheses like that and it would do the exact same thing as not putting it in any at all.

[ToonMariner]

it DOES make a difference - check your operator precedence.

 

The concatenation operator takes precedence over mathematical ones so if you want any computation within a concatenated string it must be contained within parentheses.