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Re: strpos() before str_replace()? Or, maybe strtr()?

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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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Thread

strpos() before str_replace()? Or, maybe strtr()? Jason C <jwcarlton@gmail.com> - 2014-02-16 01:49 -0800
  Re: strpos() before str_replace()? Or, maybe strtr()? bill <william@TechServSys.com> - 2014-02-16 07:10 -0500
  Re: strpos() before str_replace()? Or, maybe strtr()? "J.O. Aho" <user@example.net> - 2014-02-16 14:55 +0100
  Re: strpos() before str_replace()? Or, maybe strtr()? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-02-16 15:10 +0100
    Re: strpos() before str_replace()? Or, maybe strtr()? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-02-16 20:24 +0000
      Re: strpos() before str_replace()? Or, maybe strtr()? "J.O. Aho" <user@example.net> - 2014-02-16 21:41 +0100
        Re: strpos() before str_replace()? Or, maybe strtr()? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-02-16 20:51 +0000
          Re: strpos() before str_replace()? Or, maybe strtr()? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-02-16 22:16 +0100
            Re: strpos() before str_replace()? Or, maybe strtr()? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-02-16 23:13 +0000
              Re: strpos() before str_replace()? Or, maybe strtr()? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-02-18 01:33 +0100
          Re: strpos() before str_replace()? Or, maybe strtr()? "J.O. Aho" <user@example.net> - 2014-02-17 06:35 +0100
            Re: strpos() before str_replace()? Or, maybe strtr()? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-02-17 14:14 +0000
              Re: strpos() before str_replace()? Or, maybe strtr()? "J.O. Aho" <user@example.net> - 2014-02-17 18:55 +0100
            Re: strpos() before str_replace()? Or, maybe strtr()? Christoph Michael Becker <cmbecker69@arcor.de> - 2014-02-17 19:30 +0100
  Re: strpos() before str_replace()? Or, maybe strtr()? Jerry Stuckle <jstucklex@attglobal.net> - 2014-02-16 09:15 -0500
  Re: strpos() before str_replace()? Or, maybe strtr()? Christoph Michael Becker <cmbecker69@arcor.de> - 2014-02-16 15:45 +0100
    Re: strpos() before str_replace()? Or, maybe strtr()? Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2014-02-16 17:23 +0100
      Re: strpos() before str_replace()? Or, maybe strtr()? Christoph Michael Becker <cmbecker69@arcor.de> - 2014-02-16 17:41 +0100
  Re: strpos() before str_replace()? Or, maybe strtr()? Norman Peelman <npeelman@cfl.rr.com> - 2014-02-16 10:08 -0500
    Re: strpos() before str_replace()? Or, maybe strtr()? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-02-16 19:21 +0000
      Re: strpos() before str_replace()? Or, maybe strtr()? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-02-16 20:53 +0000
        Re: strpos() before str_replace()? Or, maybe strtr()? Denis McMahon <denismfmcmahon@gmail.com> - 2014-02-17 01:44 +0000
          Re: strpos() before str_replace()? Or, maybe strtr()? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-02-17 02:19 +0000
      Re: strpos() before str_replace()? Or, maybe strtr()? Norman Peelman <npeelman@cfl.rr.com> - 2014-02-16 18:17 -0500
  Re: strpos() before str_replace()? Or, maybe strtr()? Ben Bacarisse <ben.usenet@bsb.me.uk> - 2014-02-16 20:49 +0000

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