| Re: strpos() before str_replace()? Or, maybe strtr()? [message #184924 is a reply to message #184918] |
Sun, 16 February 2014 15:08   |
Norman Peelman
Messages: 126
Registered: September 2010
Karma:
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Senior Member |
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On 02/16/2014 04:49 AM, Jason C wrote:
> I know that I'm talking about microseconds here, so this is really just for the sake of furthering my own education.
>
> I'm looping through roughly 100,000 values:
>
> $userArr = array(
> "something" => "anything",
> ...
> );
>
> foreach ($userArr as $key => $val) {
> $firstname = str_replace($key, "****", $firstname);
> $lastname = str_replace($key, "****", $lastname);
> }
>
> Both $firstname AND $lastname could contain any of the keys, but could only potentially contain one key each. It's likely, though, that neither will contain any of the keys.
>
> Would it be faster to use strpos() before each str_replace(), like so?:
>
> foreach ($userArr as $key => $val) {
> if (strpos($firstname, $key) !== false)
> $firstname = str_replace($key, "****", $firstname);
>
> if (strpos($lastname, $key) !== false)
> $lastname = str_replace($key, "****", $lastname);
> }
>
> My instinct is that it would be the same, if not marginally slower; allowing a potential computation time for 100,002 strpos() as opposed to 100,000 str_replace().
>
> Or, would strtr() be faster? I've never actually used this function in practice; I think it's a slow function, but have never tested it, and don't remember where I read that:
>
> $firstname = strtr($firstname, $userArr);
> $lastname = strtr($lastname, $userArr);
>
> Any other suggestions on what might be the fastest option?
>
> TIA,
>
> Jason
>
Per http://us1.php.net/manual/en/function.strstr.php - 'strpos()' is
faster than 'strstr()' if you only want to know if a string exists in
another string.
As far as using:
> foreach ($userArr as $key => $val) {
> if (strpos($firstname, $key) !== false)
> $firstname = str_replace($key, "****", $firstname);
>
> if (strpos($lastname, $key) !== false)
> $lastname = str_replace($key, "****", $lastname);
> }
It's slower because you are actually performing the same function
twice on each iteration. You are asking 'strpos()' to look for a string
and report its position (if it exists). It has to look through the
entire string to do so. Then you ask 'str_replace()' to do the same
thing only replacing the found string with a new string (if it exists).
It has to look through the entire string to do so. Since you are not
using the found position of said string ('str_replace()' can't use it)
then you are making a wasted call.
--
Norman
Registered Linux user #461062
-Have you been to www.php.net yet?-
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