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php xml code explantion

Posted on 2013-11-14
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Last Modified: 2013-11-16
Please explain why this code works and the object part



 <?php // RAY_temp_rgb192.php error_reporting(E_ALL); echo '<pre>'; // SEE http://www.experts-exchange.com/Web_Development/Web_Languages-Standards/PHP/Q_28287746.html#a39633174 $url = 'http://www.experts-exchange.com/viewCodeSnippet.jsp?refID=39631349&rtid=20&icsi=3'; // THE XML FILE AT THE GIVEN $url IS UNUSABLE, SO IT'S INSERTED HERE $xml = <<<EOD <?xml version="1.0" encoding="UTF-8"?> <urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9"> <url> <loc>http://website.com/</loc> <priority>1.0</priority> </url> <url> <loc>http://www.website.com/portfolio/</loc> <priority>0.9</priority> </url> <url> <loc>http://www.website.com/about/</loc> <priority>0.9</priority> </url> <url> <loc>http://www.website.com/contact/</loc> <priority>0.9</priority> </url> <url> <loc>http://www.website.com/portfolio/branding/</loc> <priority>0.8</priority> </url> <url> <loc>http://www.website.com/portfolio/web-wordpress/</loc> <priority>0.8</priority> </url> <url> <loc>http://www.website.com/portfolio/social-media/</loc> <priority>0.8</priority> </url> <url> <loc>http://www.website.com/portfolio/print/</loc> <priority>0.8</priority> </url> <url> <loc>http://www.website.com/portfolio/branding/cabrillo-youth-summer-institute.php</loc> </url> <url> <loc>http://www.website.com/portfolio/branding/santacruz-popup-artparty.php</loc> </url> <url> <loc>http://www.website.com/portfolio/branding/red-house.php</loc> </url> <url> <loc>http://www.website.com/portfolio/branding/what-to-do-in.php</loc> </url> <url> <loc>http://www.website.com/portfolio/branding/room-service.php</loc> </url> <url> <loc>http://www.website.com/portfolio/branding/new-evolution.php</loc> </url> <url> <loc>http://www.website.com/portfolio/branding/film-production-studio.php</loc> </url> <url> <loc>http://www.website.com/portfolio/branding/rogueIBO.php</loc> </url> <url> <loc>http://www.website.com/portfolio/branding/booster-bath.php</loc> </url> <url> <loc>http://www.website.com/portfolio/branding/pilar-macchione.php</loc> </url> <url> <loc>http://www.website.com/portfolio/branding/katie-mcmahon.php</loc> </url> <url> <loc>http://www.website.com/portfolio/branding/genesis.php</loc> </url> <url> <loc>http://www.website.com/portfolio/branding/tequila-jacks.php</loc> </url> <url> <loc>http://www.website.com/portfolio/branding/em-integrated.php</loc> </url> <url> <loc>http://www.website.com/portfolio/branding/em.php</loc> </url> <url> <loc>http://www.website.com/portfolio/branding/orignauxmoose.php</loc> </url> <url> <loc>http://www.website.com/portfolio/branding/corey-gegner.php</loc> </url> <url> <loc>http://www.website.com/portfolio/branding/trey-hock.php</loc> </url> <url> <loc>http://www.website.com/portfolio/branding/nathan-jones.php</loc> </url> <url> <loc>http://www.website.com/portfolio/branding/morgan-victoria.php</loc> </url> </urlset> EOD; // MAKE AN OBJECT $obj = simplexml_load_string($xml); // USE AN ITERATOR TO RECOVER THE PARTS OF THE URL ARRAY $urlist = array(); foreach ($obj->url as $u) { $l = (string)$u->loc; $p = (string)$u->priority; $d = "$l,$p"; $d = rtrim($d, ','); $urlist[] = $d; } // SHOSW THE WORK PRODUCT print_r($urlist); 

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Question by:rgb192
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6 Comments
 
LVL 110

Expert Comment

by:Ray Paseur
ID: 39647992
The code does not work any more.  It worked when I posted it, but it appears to have been modified.  Do you have a copy of the original, with appropriate line breaks and formatting?  I do not keep copies of "RAY_temp_" scripts.
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LVL 14

Expert Comment

by:jb1dev
ID: 39649094
As other comment said, this is really hard to read with the formatting you have posted.

But I gather your question is, how does the inline xml work?
This is using something called a heredoc
See
http://www.tuxradar.com/practicalphp/2/6/3

In your example, the code is using "EOD" (this can be anything, but usually people use EOD as short for "end of document")
So the string:
$xml = <<<EOD

is initialized to all the subsequent text until reaching a single line starting with "EOD"

It then attempts to load that xml document (from the string $xml) using this function:

$obj = simplexml_load_string($xml)

which appears to return an object.
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LVL 110

Expert Comment

by:Ray Paseur
ID: 39649153
Note on HEREDOC... The end-of-document delimiter must start in column 1.  That is one of the reasons for keeping the original formatting.
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Author Comment

by:rgb192
ID: 39651078
<?php // RAY_temp_rgb192.php
error_reporting(E_ALL);
echo '<pre>';

// SEE http://www.experts-exchange.com/Web_Development/Web_Languages-Standards/PHP/Q_28287746.html#a39633174

$url = 'http://www.experts-exchange.com/viewCodeSnippet.jsp?refID=39631349&rtid=20&icsi=3';

// THE XML FILE AT THE GIVEN $url IS UNUSABLE, SO IT'S INSERTED HERE
$xml = <<<EOD
<?xml version="1.0" encoding="UTF-8"?>
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9"> <url> <loc>http://website.com/</loc> <priority>1.0</priority> </url> <url> <loc>http://www.website.com/portfolio/</loc> <priority>0.9</priority> </url> <url> <loc>http://www.website.com/about/</loc> <priority>0.9</priority> </url> <url> <loc>http://www.website.com/contact/</loc> <priority>0.9</priority> </url> <url> <loc>http://www.website.com/portfolio/branding/</loc> <priority>0.8</priority> </url> <url> <loc>http://www.website.com/portfolio/web-wordpress/</loc> <priority>0.8</priority> </url> <url> <loc>http://www.website.com/portfolio/social-media/</loc> <priority>0.8</priority> </url> <url> <loc>http://www.website.com/portfolio/print/</loc> <priority>0.8</priority> </url> <url> <loc>http://www.website.com/portfolio/branding/cabrillo-youth-summer-institute.php</loc> </url> <url> <loc>http://www.website.com/portfolio/branding/santacruz-popup-artparty.php</loc> </url> <url> <loc>http://www.website.com/portfolio/branding/red-house.php</loc> </url> <url> <loc>http://www.website.com/portfolio/branding/what-to-do-in.php</loc> </url> <url> <loc>http://www.website.com/portfolio/branding/room-service.php</loc> </url> <url> <loc>http://www.website.com/portfolio/branding/new-evolution.php</loc> </url> <url> <loc>http://www.website.com/portfolio/branding/film-production-studio.php</loc> </url> <url> <loc>http://www.website.com/portfolio/branding/rogueIBO.php</loc> </url> <url> <loc>http://www.website.com/portfolio/branding/booster-bath.php</loc> </url> <url> <loc>http://www.website.com/portfolio/branding/pilar-macchione.php</loc> </url> <url> <loc>http://www.website.com/portfolio/branding/katie-mcmahon.php</loc> </url> <url> <loc>http://www.website.com/portfolio/branding/genesis.php</loc> </url> <url> <loc>http://www.website.com/portfolio/branding/tequila-jacks.php</loc> </url> <url> <loc>http://www.website.com/portfolio/branding/em-integrated.php</loc> </url> <url> <loc>http://www.website.com/portfolio/branding/em.php</loc> </url> <url> <loc>http://www.website.com/portfolio/branding/orignauxmoose.php</loc> </url> <url> <loc>http://www.website.com/portfolio/branding/corey-gegner.php</loc> </url> <url> <loc>http://www.website.com/portfolio/branding/trey-hock.php</loc> </url> <url> <loc>http://www.website.com/portfolio/branding/nathan-jones.php</loc> </url> <url> <loc>http://www.website.com/portfolio/branding/morgan-victoria.php</loc> </url> </urlset>
EOD;

// MAKE AN OBJECT
$obj = simplexml_load_string($xml);

// USE AN ITERATOR TO RECOVER THE PARTS OF THE URL ARRAY
$urlist = array();
foreach ($obj->url as $u)
{
    $l = (string)$u->loc;
    $p = (string)$u->priority;
    $d = "$l,$p";
    $d = rtrim($d, ',');
    $urlist[] = $d;
}

// SHOSW THE WORK PRODUCT
print_r($urlist);

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Sorry, mobile.ee to copy paste PREVIOUSLY
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LVL 110

Accepted Solution

by:
Ray Paseur earned 500 total points
ID: 39651302
The script uses the SimpleXML class to create an object from the XML string.  In PHP both arrays and objects are iteratible, so you can use foreach() to process objects iteratively, drawing out data elements one at a time in sequence.  That is what we are doing with the $l and $p variables.  In some cases the $p variable does not exists, so after concatenating the $l,$p, we use rtrim() to remove the trailing comma, if any.

Programming with PHP is only about the data, and that is all that PHP does -- transform data from one form to another.  We can use print_r() to visualize the data.  In the case of the $obj variable, it is an object that contains an array of smaller objects.  It looks like this:

SimpleXMLElement Object
(
    [url] => Array
        (
            [0] => SimpleXMLElement Object
                (
                    [loc] => http://website.com/
                    [priority] => 1.0
                )

            [1] => SimpleXMLElement Object
                (
                    [loc] => http://www.website.com/portfolio/
                    [priority] => 0.9
                )

            [2] => SimpleXMLElement Object
                (
                    [loc] => http://www.website.com/about/
                    [priority] => 0.9
                )

            [3] => SimpleXMLElement Object
                (
                    [loc] => http://www.website.com/contact/
                    [priority] => 0.9
                )

            [4] => SimpleXMLElement Object
                (
                    [loc] => http://www.website.com/portfolio/branding/
                    [priority] => 0.8
                )

            [5] => SimpleXMLElement Object
                (
                    [loc] => http://www.website.com/portfolio/web-wordpress/
                    [priority] => 0.8
                )

            [6] => SimpleXMLElement Object
                (
                    [loc] => http://www.website.com/portfolio/social-media/
                    [priority] => 0.8
                )

            [7] => SimpleXMLElement Object
                (
                    [loc] => http://www.website.com/portfolio/print/
                    [priority] => 0.8
                )

            [8] => SimpleXMLElement Object
                (
                    [loc] => http://www.website.com/portfolio/branding/cabrillo-youth-summer-institute.php
                )

            [9] => SimpleXMLElement Object
                (
                    [loc] => http://www.website.com/portfolio/branding/santacruz-popup-artparty.php
                )

            [10] => SimpleXMLElement Object
                (
                    [loc] => http://www.website.com/portfolio/branding/red-house.php
                )

            [11] => SimpleXMLElement Object
                (
                    [loc] => http://www.website.com/portfolio/branding/what-to-do-in.php
                )

            [12] => SimpleXMLElement Object
                (
                    [loc] => http://www.website.com/portfolio/branding/room-service.php
                )

            [13] => SimpleXMLElement Object
                (
                    [loc] => http://www.website.com/portfolio/branding/new-evolution.php
                )

            [14] => SimpleXMLElement Object
                (
                    [loc] => http://www.website.com/portfolio/branding/film-production-studio.php
                )

            [15] => SimpleXMLElement Object
                (
                    [loc] => http://www.website.com/portfolio/branding/rogueIBO.php
                )

            [16] => SimpleXMLElement Object
                (
                    [loc] => http://www.website.com/portfolio/branding/booster-bath.php
                )

            [17] => SimpleXMLElement Object
                (
                    [loc] => http://www.website.com/portfolio/branding/pilar-macchione.php
                )

            [18] => SimpleXMLElement Object
                (
                    [loc] => http://www.website.com/portfolio/branding/katie-mcmahon.php
                )

            [19] => SimpleXMLElement Object
                (
                    [loc] => http://www.website.com/portfolio/branding/genesis.php
                )

            [20] => SimpleXMLElement Object
                (
                    [loc] => http://www.website.com/portfolio/branding/tequila-jacks.php
                )

            [21] => SimpleXMLElement Object
                (
                    [loc] => http://www.website.com/portfolio/branding/em-integrated.php
                )

            [22] => SimpleXMLElement Object
                (
                    [loc] => http://www.website.com/portfolio/branding/em.php
                )

            [23] => SimpleXMLElement Object
                (
                    [loc] => http://www.website.com/portfolio/branding/orignauxmoose.php
                )

            [24] => SimpleXMLElement Object
                (
                    [loc] => http://www.website.com/portfolio/branding/corey-gegner.php
                )

            [25] => SimpleXMLElement Object
                (
                    [loc] => http://www.website.com/portfolio/branding/trey-hock.php
                )

            [26] => SimpleXMLElement Object
                (
                    [loc] => http://www.website.com/portfolio/branding/nathan-jones.php
                )

            [27] => SimpleXMLElement Object
                (
                    [loc] => http://www.website.com/portfolio/branding/morgan-victoria.php
                )

        )

)

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In the case of the $urlist array, it looks like this:

Array
(
    [0] => http://website.com/,1.0
    [1] => http://www.website.com/portfolio/,0.9
    [2] => http://www.website.com/about/,0.9
    [3] => http://www.website.com/contact/,0.9
    [4] => http://www.website.com/portfolio/branding/,0.8
    [5] => http://www.website.com/portfolio/web-wordpress/,0.8
    [6] => http://www.website.com/portfolio/social-media/,0.8
    [7] => http://www.website.com/portfolio/print/,0.8
    [8] => http://www.website.com/portfolio/branding/cabrillo-youth-summer-institute.php
    [9] => http://www.website.com/portfolio/branding/santacruz-popup-artparty.php
    [10] => http://www.website.com/portfolio/branding/red-house.php
    [11] => http://www.website.com/portfolio/branding/what-to-do-in.php
    [12] => http://www.website.com/portfolio/branding/room-service.php
    [13] => http://www.website.com/portfolio/branding/new-evolution.php
    [14] => http://www.website.com/portfolio/branding/film-production-studio.php
    [15] => http://www.website.com/portfolio/branding/rogueIBO.php
    [16] => http://www.website.com/portfolio/branding/booster-bath.php
    [17] => http://www.website.com/portfolio/branding/pilar-macchione.php
    [18] => http://www.website.com/portfolio/branding/katie-mcmahon.php
    [19] => http://www.website.com/portfolio/branding/genesis.php
    [20] => http://www.website.com/portfolio/branding/tequila-jacks.php
    [21] => http://www.website.com/portfolio/branding/em-integrated.php
    [22] => http://www.website.com/portfolio/branding/em.php
    [23] => http://www.website.com/portfolio/branding/orignauxmoose.php
    [24] => http://www.website.com/portfolio/branding/corey-gegner.php
    [25] => http://www.website.com/portfolio/branding/trey-hock.php
    [26] => http://www.website.com/portfolio/branding/nathan-jones.php
    [27] => http://www.website.com/portfolio/branding/morgan-victoria.php
)

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HTH, ~Ray
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Author Closing Comment

by:rgb192
ID: 39653170
The script uses the SimpleXML class to create an object from the XML string.  In PHP both arrays and objects are iteratible, so you can use foreach() to process objects iteratively, drawing out data elements one at a time in sequence.  That is what we are doing with the $l and $p variables.  In some cases the $p variable does not exists, so after concatenating the $l,$p, we use rtrim() to remove the trailing comma, if any.


Thanks
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