Xml data extraction using php

I know that php has many ways to retrieve data from xml through php. the most convenient way is to use regular expressions. but what should I do if I use DOM?
I am not very familiar with Baidu. please explain it to me.
For example

20110524

13.82

13.94

13.79

13.85


20110525

13.82

13.86

13.58

13.60


What should I do if I want to get the corresponding value through the id attribute of this xml segment?
I am the first:
Preg_match_all ("/\ (.*?) \ <\/Value \>/", $ Result, $ array); Operation after obtaining the Value;
Second:
$ Doc = new DOMDocument ();
$ Doc-> load ('sixx. XML'); // read the xml file
$ Results = $ doc-> getElementsByTagName ("Record ");
Foreach ($ Results as $ Result ){
$ Records = $ Result-> getElementsByTagName ("Item ");
$ Times = $ Records-> item (0)-> nodeValue;
}
Locate Item to continue operation
I want to know what to do if I use the XML id to retrieve data?
I tried getElementById () to get it. the system prompts that this method is not available...
Call to undefined method DOMElement: getElementById ().
Thank you for your help.

Reply to discussion (solution)

$s =<<< XML
  
   
    
     
      20110524
     
    
    
     
      13.82
     
    
    
     
      13.94
     
    
    
     
      13.79
     
    
    
     
      13.85
     
    
   
   
    
     
      20110525
     
    
    
     
      13.82
     
    
    
     
      13.86
     
    
    
     
      13.58
     
    
    
     
      13.60
     
    
   
  XML;$xml = simplexml_load_string($s);$t = $xml->xpath('//*[@Id="8"]');print_r($t);

Array(    [0] => SimpleXMLElement Object        (            [@attributes] => Array                (                    [Id] => 8                )            [Value] => 13.94        )    [1] => SimpleXMLElement Object        (            [@attributes] => Array                (                    [Id] => 8                )            [Value] => 13.86        ))

This is my xml file (the file name is 6.xml). I want to use SimpleXML to process the document, but why cannot I retrieve the data?
The code is as follows:
$ Xml = simplexml_load_file ('6. XML ');
Foreach ($ xml-> Item as $ ){
Echo $ a-> Value;
}
?>
The running result is empty .. I think the code is okay ..

No problem

  Item as $a ){     echo $a->Value . '
';}

2011052413.8213.9413.7913.852011052513.8213.8613.5813.60

Use simplexml_load_file or simplexml_load_string to convert xml into an array.
Reference: http://php.net/manual/en/function.simplexml-load-file.php

I read the information on the official website, and then read the subsequent code. I found that the data can be retrieved. However, there is still a problem, that is, the value of the obtained array fails to be obtained by using the id that was first mentioned.

Result (printr_r ($ t )):
Array
(
[0] => SimpleXMLElement Object
(
[@ Attributes] => Array
(
[Id] => 8
)

[Value] = & gt; 13.94
)

[1] => SimpleXMLElement Object
(
[@ Attributes] => Array
(
[Id] => 8
)

[Value] = & gt; 13.86
)

)
To obtain specific data,
I used echo $ t-> Value;
And echo $ t-> Id;
Data cannot be obtained.
I am grateful for not understanding XML arrays.