PHP: How to Replace a String Between Tags
Nearly all Web data exchange formats, from HTML to XML, use tags as a way to separate data into usable bits. However, working directly with the data using the most basic string functions in PHP can be a challenge. It is for this reason that PHP supports regular expressions (regex), an industry standard syntax that can be used to perform complex find and replace operations on strings. Using regex, you define a pattern that PHP searches for and how it ought to be replaced.
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Instructions
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Open a text editor or your favorite PHP Integrated Development Environment (IDE).
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Type or paste the following into your editor:
#!/usr/bin/php
<?php
$tags = '<xml>Some data between two xml tags</xml>';
$pattern = '/<(\w+)>.+<\/\w+>/s';
$replacement = '<${1}>This is a replacement</${1}>';
echo preg_replace($pattern, $replacement, $tags);
?>
The key lines are the ones that begin with "$pattern" and "$replacement." The pattern looks for a word between two arrow brackets to be the tag, some information between the tags and another closing tag between arrow brackets with a backslash.
The "replacement" pattern rebuilds the found string from scratch using the originally detected tag and the new text.
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Save your work and double-click the file to run it through PHP. The output will be:
<xml>This is a replacement</xml>
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Tips & Warnings
Regex syntax is a complicated subject; see Resources to learn more about it.
