Why Are Short PHP Tags Disabled in PHP 5.3.1 and How Can I Re-enable Them?

Short Tags Disabled in PHP 5.3.1

PHP 5.3.1 introduces a departure from previous versions regarding the handling of short PHP tags (). These tags are now disabled by default, prompting confusion among users who have relied on them in their applications.

Reasons for Deprecation

Short tags are discouraged due to their potential for ambiguity, especially in scenarios where code is interpreted by both PHP and another language like XML. This can lead to unintended code execution and security vulnerabilities.

Alternative Approaches

PHP recommends using the full PHP tags (;) to ensure compatibility and portability of applications. Short echo tags (<= $var ?>) remain available regardless of PHP settings and provide a concise alternative to .

Re-enabling Short Tags

If you must use short tags, you can enable them using the following methods:

• Set short_open_tag = On in your php.ini file.
• Call ini_set("short_open_tag", 1); in your code.

• Add the following line to your .htaccess file:

  php_value short_open_tag 1

Historical Behavior

PHP 5.3 is the first version to disable short tags by default, as shown in the table below:

PHP Version	Default Behavior
4, 5.0	On
5.1, 5.2	On (recommended off)
5.3	Off

PHP strongly recommends discontinuing the use of short tags to maintain code clarity and avoid potential conflicts.

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