Master PHP Debugging: Essential Tips and Best Practices

Enable Error Reporting

In PHP you can set the error reporting level to capture all errors. In a development environment, set it to E_ALL and enable display of errors. Add the following lines to your script:

error_reporting(E_ALL);
ini_set('display_errors', 1);

Use Logging

Logging is another common debugging technique. Use the built‑in error_log function to write messages to a log file.

error_log('Error message', 3, '/path/to/error.log');

This writes the error message to the specified file (or to the default PHP error log if no path is provided).

Use Breakpoints

Breakpoints pause execution at a specific line so you can inspect variables and program state. In PHP, install the Xdebug extension and enable it in php.ini. Then call xdebug_break() to set a breakpoint.

function debugFunction() {
    $a = 10;
    $b = 20;
    xdebug_break();
    $c = $a + $b;
    echo $c;
}

When execution reaches xdebug_break(), the script pauses and you can use a debugger such as PHPStorm to view variable values and the call stack.

Catch Exceptions with try‑catch

Exceptions represent runtime errors. Wrap code that may throw an exception in a try block and handle it in a catch block, for example:

try {
    // code that may throw an exception
} catch (Exception $e) {
    // handle exception, e.g., log error or show a friendly error page
}

Place potentially risky code inside the try block; if an exception occurs, the catch block runs.

Use var_dump and print_r

var_dump

and print_r are essential debugging functions that output variable values and types.

$a = array('apple', 'orange', 'banana');
var_dump($a);

The above prints detailed information about $a, including its values and type.

By enabling error reporting, using logging, setting breakpoints, catching exceptions, and employing var_dump / print_r, you can more effectively debug PHP code. Successful debugging also requires proactive analysis of code logic to pinpoint and resolve issues.