Still celebrating National IT Professionals Day with 3 months of free Premium Membership. Use Code ITDAY17

x
?
Solved

Should i Use regexp or string functions

Posted on 2011-02-23
9
Medium Priority
?
383 Views
Last Modified: 2012-05-11
Hi experts!

Please tell me which one is going to be quicker to find and get from string couple of characters.

I want to search through a long string to find match for a youtube id, I don't know where it is going to be. I know the pattern that will occur - youtube.com/v/videoid&...

How do i accomplish this?
What is the fastest way as far as performance is considered?

Many thanks!
0
Comment
Question by:vidda22
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 4
  • 4
9 Comments
 
LVL 34

Expert Comment

by:Beverley Portlock
ID: 34962203
Quick answer: substr is ALWAYS faster

but....

If a pattern is always fixed then using substr will be faster than a regex, but if a pattern is variable then using a regex will be a lot less error prone than messing about with substr.

You should not be worrying about "which one is going to be quicker" because the difference in execution time is tiny - a fraction of a millisecond. Worry about using the right tool for the job instead.

In terms of speed, your MySQL database will have a bigger impact than substr/regex and your customer's ADSL line will have the biggest impact of all because it is usually the slowest component in the whole chain.
0
 

Author Comment

by:vidda22
ID: 34962291
Ok. Thanks bportlock!

Obviously I don't know the videoid.

Could you please tell me how would I take the id using substr?
having this pattern:

.....youtube.com/v/videoid&...


Would substring help me to get couple of these if there were more of them in a string?

If not what code should i use as far as regexp is considered?
0
 
LVL 34

Accepted Solution

by:
Beverley Portlock earned 2000 total points
ID: 34962367
If you don't know where a substring would turn up in a string (or how many times) then that is a job for a regex, so in your example I would use a preg_match_all and a pattern like '#youtube\.com/v/([^&]+)&amp#s'

UNTESTED

$mystring = ..... string containing what you want to search
preg_match_all( '#youtube\.com/v/([^&]+)&amp#s', $mysting, $matches );
print_r( $matches );

I'm assuming that 'videoId' is where you expect to find the video ID
0
What does it mean to be "Always On"?

Is your cloud always on? With an Always On cloud you won't have to worry about downtime for maintenance or software application code updates, ensuring that your bottom line isn't affected.

 
LVL 111

Expert Comment

by:Ray Paseur
ID: 34962374
Please post a sample of your test data.  We can help you isolate the information you need.  You may want to use preg_match_all()
http://php.net/manual/en/function.preg-match-all.php

I agree with Brian's characterization that substr() is faster than REGEX.  At the same time, I expect that speed does not matter here.  The CPU is about 100,000 times faster than the disk drives (give or take a few orders of magnitude) so optimizing any purely-CPU operation like string manipulation is milking a mouse.  A lot of effort for very little result.  If you have a performance problem it will always be in the I/O subsystem.  In web sites that means the data base.
0
 
LVL 34

Expert Comment

by:Beverley Portlock
ID: 34962377
0
 

Author Comment

by:vidda22
ID: 34962405
Thanks!
0
 

Author Comment

by:vidda22
ID: 34962505
I used this:

$videoText = '"<http://www.youtube.com/v/YLwZwheyeEc&setting=1>"';

if((bool)preg_match_all( '#youtube\.com/v/([^&]+)&amp#s',$videoText,$matches)){//w{3}\.youtube\.com\/v\/([A-Za-z0-9]{9,12})>$
            print_r($matches);
      }

And result is
Array ( [0] => Array ( [0] => youtube.com/v/YLwZwheyeEc& ) [1] => Array ( [0] => YLwZwheyeEc ) )

I don't want anything else than videoid how do i do that??
so i want to get rid of matches like [0]
0
 

Author Comment

by:vidda22
ID: 34962520
I used this code sorry

$videoText = '"<http://www.youtube.com/v/YLwZwheyeEc&setting=1>"';

if((bool)preg_match_all( '#youtube\.com/v/([^&]+)&amp#s',$videoText,$matches)){
            print_r($matches);
      }
0
 
LVL 34

Expert Comment

by:Beverley Portlock
ID: 34962814
"so i want to get rid of matches like [0]"

$matches[0] is always present, just ignore it. The results are always in $matches[1] onwards depending on the preg options you select
0

Featured Post

Concerto Cloud for Software Providers & ISVs

Can Concerto Cloud Services help you focus on evolving your application offerings, while delivering the best cloud experience to your customers? From DevOps to revenue models and customer support, the answer is yes!

Learn how Concerto can help you.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

Since pre-biblical times, humans have sought ways to keep secrets, and share the secrets selectively.  This article explores the ways PHP can be used to hide and encrypt information.
Many old projects have bad code, but the budget doesn't exist to rewrite the codebase. You can update this code to be safer by introducing contemporary input validation, sanitation, and safer database queries.
The viewer will learn how to count occurrences of each item in an array.
The viewer will learn how to create and use a small PHP class to apply a watermark to an image. This video shows the viewer the setup for the PHP watermark as well as important coding language. Continue to Part 2 to learn the core code used in creat…

715 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question