Debugging

Enabling Error Display

By default, PHP may hide errors. Enable them during development:

<?php
error_reporting(E_ALL);           // Report all errors
ini_set('display_errors', 1);     // Show errors on screen

Place this at the top of your script or in a config file.

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var_dump()

Shows the type and value of a variable. Best for debugging.

$name = "John";
$age = 25;
$prices = [10, 20, 30];

var_dump($name);
// string(4) "John"

var_dump($age);
// int(25)

var_dump($prices);
// array(3) { [0]=> int(10) [1]=> int(20) [2]=> int(30) }

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print_r()

Displays arrays and objects in a human-readable format. Easier to read than var_dump() but shows less detail.

$user = [
    'name' => 'John',
    'email' => 'john@example.com',
    'roles' => ['admin', 'editor']
];

print_r($user);
// Array
// (
//     [name] => John
//     [email] => john@example.com
//     [roles] => Array
//         (
//             [0] => admin
//             [1] => editor
//         )
// )

Wrap in <pre> for Better Formatting

echo '<pre>';
print_r($user);
echo '</pre>';

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Quick Debugging Pattern

A common pattern for quick debugging:

echo '<pre>';
var_dump($variable);
echo '</pre>';
die();  // Stop execution here

Or as a one-liner:

die(var_dump($variable));

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Error Reporting Levels

Constant	Description
E_ALL	All errors and warnings
E_ERROR	Fatal runtime errors
E_WARNING	Runtime warnings
E_NOTICE	Runtime notices

// Show all errors except notices
error_reporting(E_ALL & ~E_NOTICE);

// Show only errors and warnings
error_reporting(E_ERROR | E_WARNING);

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Tips

• Always disable error display in production use logging instead
• Use var_dump() over echo for debugging, it shows the type
• Check your PHP error log for errors that don’t display on screen
• Use exit or die() to stop execution at a specific point