in PHP, how to append incremental value to each tag

Question

I have a bunch of  tags in an HTML file that I would like to append a unique value to, for example, my HTML file has the following (i've dumped this HTML file into a PHP variable using file_get_contents):

<P> ... data ... </P>
<P> ... data ... </P>
<P> ... data ... </P>
<P> ... data ... </P>
<P> ... data ... </P>

I would like to change it so it reads this instead:

<P id='unique1'> ... data ... </P>
<P id='unique2'> ... data ... </P>
<P id='unique3'> ... data ... </P>
<P id='unique4'> ... data ... </P>
<P id='unique5'> ... data ... </P>

Since this is a regular HTML file, there are other tags that may reside in the file as well (such as <HTML>, <HEAD>, <STYLE>, <BODY>, etc., but I want to append a unique id to ALL  tags

Why do you need that? Both JavaScript and CSS can find those easily without the IDs. — Gordon, Jan 24 '11 at 09:12
possible duplicate of [Regular expression for grabbing the href attribute of an A element](http://stackoverflow.com/questions/3820666/regular-expression-for-grabbing-the-href-attribute-of-an-a-element) - the accepted answer shows how to fetch arbitrary tags by name and check/get/set their attributes. — Gordon, Jan 24 '11 at 09:15
Agreeing with @Gordon. If you're not even generating the HTML by hand but just want to automatically number all tags, you may just as well enumerate all `
` tags in Javascript, forgoing ids altogether. — deceze, Jan 24 '11 at 09:16
Gordon, thanks for the link on how to get and set attributes, I will try that! — James Nine, Jan 24 '11 at 09:26

score 2 · Answer 1 · answered Jan 24 '11 at 09:17

You could simply do this...

$Count = count($MyData);
for ($i = 0; $i < $Count; ++$i) {
    echo '<p id="id_' . $MyData[$i]->Id . '">... data ... </p>';
}

Or even this...

$Count = count($MyData);
for ($i = 0; $i < $Count; ++$i) {
    echo '<p id="id_' . $i . '">... data ... </p>';
}

Just bear in mind that HTML id attributes must begin with a letter, not a number!

score 2 · Accepted Answer · answered Jan 24 '11 at 09:23

You need to write a little HTML parser. You can take this as starting point:

<?php

$html = '<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head><title></title>
</head>
<body>

<P> ... data ... </P>
<P> ... data ... </P>
<P> ... data ... </P>
<P> ... data ... </P>
<P> ... data ... </P>

</body>
</html>';

$dom = new DOMDocument;
$dom->loadHTML($html);

$paragraphs = $dom->getElementsByTagName('p');
$count = 0;
foreach($paragraphs as $p){
    $count++;
    $p->setAttribute('id', 'unique' . $count);
}

echo $dom->saveHTML();

In any case, parsing HTML is not trivial task and handling a list of random IDs in JavaScript is not trivial either. Make sure you have a reason to do all this.

score 0 · Answer 3 · answered Jan 24 '11 at 09:36

You could use a template engine like Smarty where you can use tags like this to loop over a collection of data:

{foreach from=$myItemsArray item=currentItem}
    <p id='unique{$currentItem.id}'>{$currentItem.data}</p>
{/foreach}

This is only reasonable if your page has a certain size and if the data in the HTML file can be generated from a database.

If you really need to process an already existent HTML file, you could use REGEX to replace each tag with . In PHP the functions are preg_replace or preg_replace_callback. I think if you use preg_replace you need to call it for each occurence of with a limit of 1 so you can increase a counter after every call and then use this counter to replace with . This is quite inefficient, that's why i'd recommand using preg_replace_callback where a callback function is executed each time a match is found. I hope it works to increase a counter inside this callback function (I didn't try it).

in PHP, how to append incremental value to each tag

3 Answers3