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
Solved

url_exists returns false for existing url

Posted on 2009-05-20
8
631 Views
Last Modified: 2012-08-13
I use the function url_exists() to check whether a url exists (wow). For one set of urls, this doesn't work.

- For the same domain but different urls, the functions works correctly.
- When I download the xml file and save it locally, and run the function using the local url it works.

The headers I get back are as follows:

[0] => HTTP/1.1 200 OK
[1] => Date: Wed, 20 May 2009 15:26:22 GMT
[2] => Server: Apache/2.2.8 (Win32) mod_ssl/2.2.8 OpenSSL/0.9.8k
[3] => Last-Modified: Wed, 20 May 2009 15:21:54 GMT
[4] => ETag: "12d00000000006c-2635-46a59965b054e"
[5] => Accept-Ranges: bytes
[6] => Content-Length: 9781
[7] => Connection: close
[8] => Content-Type: application/xml

Any ideas what could cause this problem?
<?php
function url_exists($url) 
{
   $hdrs = get_headers($url);
    return is_array($hdrs) ? preg_match('/^HTTP\\/\\d+\\.\\d+\\s+2\\d\\d\\s+.*$/',$hdrs[0]) : false;
} 
?>

Open in new window

0
Comment
Question by:R7AF
  • 5
  • 3
8 Comments
 
LVL 16

Expert Comment

by:jessc7
ID: 24433981
I'm not sure all the escaping is necessary, is it? The following works for me using an online expression checker:

^HTTP\/\d+\.\d+\s+2\d\d\s+.*$

http://www.nvcc.edu/home/drodgers/ceu/resources/test_regexp.asp

Here is an alternative using CURL:
http://www.ajaxapp.com/2009/03/23/to-validate-if-an-url-exists-use-php-curl/
0
 
LVL 16

Expert Comment

by:jessc7
ID: 24434068
Here are two screenshots of the regex. I'm still thinking through why your original works sometimes...
original-fail.png
succeed.png
0
 
LVL 16

Accepted Solution

by:
jessc7 earned 500 total points
ID: 24434275
OK, I just testing your original regex on a test server using preg_match, and it was fine. I'm wondering if you can make your regex slightly less strict?

^HTTP\/\d+\.\d+.+2\d\d

This doesn't get so strict on the use of white space.
0
Enterprise Mobility and BYOD For Dummies

Like “For Dummies” books, you can read this in whatever order you choose and learn about mobility and BYOD; and how to put a competitive mobile infrastructure in place. Developed for SMBs and large enterprises alike, you will find helpful use cases, planning, and implementation.

 
LVL 16

Expert Comment

by:jessc7
ID: 24434288
Screenshot of validation results.
new1.png
0
 
LVL 13

Author Comment

by:R7AF
ID: 24434636
Thank you! I will test this on Friday and let you know if it solved my problem.
0
 
LVL 16

Expert Comment

by:jessc7
ID: 24529800
Hi R7AF, were you able to complete further testing on this issue?
0
 
LVL 13

Author Comment

by:R7AF
ID: 24572264
Yes, and the issue still exists. I'll try to update this question soon.
0
 
LVL 13

Author Closing Comment

by:R7AF
ID: 31583560
Thanks for your input. I'm closing this question now. Maybe I'll look into it in the future again, and will post another question about it then.
0

Featured Post

VMware Disaster Recovery and Data Protection

In this expert guide, you’ll learn about the components of a Modern Data Center. You will use cases for the value-added capabilities of Veeam®, including combining backup and replication for VMware disaster recovery and using replication for data center migration.

Question has a verified solution.

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

I imagine that there are some, like me, who require a way of getting currency exchange rates for implementation in web project from time to time, so I thought I would share a solution that I have developed for this purpose. It turns out that Yaho…
Things That Drive Us Nuts Have you noticed the use of the reCaptcha feature at EE and other web sites?  It wants you to read and retype something that looks like this.Insanity!  It's not EE's fault - that's just the way reCaptcha works.  But it is …
Learn how to match and substitute tagged data using PHP regular expressions. Demonstrated on Windows 7, but also applies to other operating systems. Demonstrated technique applies to PHP (all versions) and Firefox, but very similar techniques will w…
Explain concepts important to validation of email addresses with regular expressions. Applies to most languages/tools that uses regular expressions. Consider email address RFCs: Look at HTML5 form input element (with type=email) regex pattern: T…

860 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