Troubleshooting and Solutions for PHP Code Displaying Instead of Executing in Browser

Problem Phenomenon and Background Analysis

During web development, PHP developers frequently encounter a typical issue: PHP code displays as plain text in browsers instead of execution results. This phenomenon usually indicates that the web server fails to properly parse and execute PHP files. According to user feedback, even when Apache server runs normally and PHP files open correctly, the code still appears as HTML tags in the browser's source code.

Core Troubleshooting Steps

To resolve the issue of PHP code not executing, systematic investigation from multiple levels is required. Here are the key checkpoints summarized from actual cases:

PHP Runtime Environment Verification

First, confirm whether PHP is correctly installed and running. Use the command line tool to execute the version check command:

php -v

This command should return PHP version information. If error messages appear or the command is unrecognized, it indicates PHP installation issues, requiring reinstallation or environment variable configuration.

Apache Module Configuration Check

Apache server needs to load the PHP module to support PHP file parsing. In Apache's httpd.conf configuration file, there should be module loading directives similar to:

LoadModule php7_module "c:/php/php7apache2_4.dll"

Ensure this configuration line is not commented out (no semicolon at the beginning) and the path points to the correct PHP module file. Module filenames may vary for different PHP and Apache versions.

MIME Type Configuration Verification

Apache needs to explicitly know how to handle .php files. The httpd.conf should include MIME type definition:

AddType application/x-httpd-php .php

This configuration tells Apache to process .php files as PHP scripts. Similarly, ensure this configuration is uncommented and syntactically correct.

File Extension Confirmation

Ensure files are actually saved with .php extension. Developers might unintentionally save files as .txt or .html format, causing the server to fail recognizing them as PHP files. Correct filenames should resemble:

index.php
config.php
user_profile.php

PHP Tag Syntax Specifications

PHP code must use correct tag syntax. Although PHP supports short tags <?, many servers disable this feature by default. It's recommended to always use standard tags:

<?php
// PHP code
?>

If short tags are needed, enable them in the php.ini configuration file:

short_open_tag = On

Correct Access Method

PHP files must be accessed through the web server using HTTP protocol rather than local file protocol. The correct access method is:

http://localhost/filename.php

Instead of:

file:///C:/xampp/htdocs/filename.php

Accessing via local file protocol bypasses the web server, preventing PHP code from being executed.

Actual Case Analysis

Referring to the specific case provided by the user, the problem occurred when using short tags <? to include configuration files. In default server environments, the short tag feature is usually disabled, causing code to fail proper parsing. The issue was resolved by modifying to standard tags:

<?php
include_once("/code/configs.php");
?>

Extended Configuration Considerations

For environments using newer PHP versions, additional module configuration might be necessary. For example, in PHP 7 environments, relevant proxy modules can be enabled:

sudo a2enmod proxy_fcgi setenvif
sudo a2enconf php7.0-fpm
sudo service apache2 restart

These commands apply to Debian-based Linux systems, ensuring proper integration between PHP-FPM and Apache.

Permissions and Security Configuration

Beyond basic parsing issues, file permissions and directory configuration need consideration. The web server user (such as www-data) should have appropriate read permissions for PHP files and related directories. Meanwhile, document root and PHP handler need correct settings in virtual host configuration.

Summary and Best Practices

The issue of PHP code not executing typically stems from configuration errors rather than code problems. Developers are advised to establish standardized environment checklists including: PHP installation status, Apache module configuration, MIME type settings, file naming conventions, tag syntax selection, and access method confirmation. Through systematic troubleshooting methods, most PHP execution environment issues can be quickly identified and resolved, ensuring normal operation of web applications.