PHP Error Handling error_reporting() Function

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The PHP Error Handling error_reporting() function is used to specify which errors should be displayed or logged during code execution. It displays exact error messages to help developers find and resolve errors.

You can choose whether to show all mistakes, none, or only certain types of difficulties. This is useful for debugging during development and keeping the site secure in production. Using error_reporting() makes your PHP program more dependable and manageable.

Syntax

Below is the syntax of the PHP Error Handling error_reporting() function −

int error_reporting ( ?int $error_level = null )

Parameters

This function accepts $error_level parameter which specifies the error report level for the current script. Value number and constant name are accepted.

Return Value

The error_reporting() function returns the error_reporting level before it is set to error_level.

Report levels

Here are the reports level listed in the below table −

PHP Version

First introduced in core PHP 4, the error_reporting() function continues to function easily in PHP 5, PHP 7, and PHP 8.

Example 1

Here is the basic example of the PHP Error Handling error_reporting() function to display all PHP errors and the constant E_ALL. This helps with debugging during the development process.

<?php
   // Enable reporting of all errors
   error_reporting(E_ALL);

   // Undefined variable (will show an error)
   echo $undefinedVariable;
?>

Output

Here is the outcome of the following code −

Warning: Undefined variable $undefinedVariable in /Users/abc/Desktop/PhpProjects/index.php on line 12

Example 2

This program shows how to block all errors by setting error_reporting() function to zero. This is useful when you do not want error messages to appear on a live website.

<?php
   // Disable all error reporting
   error_reporting(0);

   // Undefined variable 
   echo "No error will be displayed";
   echo $undefinedVariable;
?> 

Output

This will generate the below output −

No error will be displayed

Example 3

This program demonstrates how to dynamically alter the error reporting level using the error_reporting() method during script execution. It starts with all errors allowed before moving to no error reporting.

<?php
   // Enable all errors
   error_reporting(E_ALL);
   echo "All errors are currently displayed.\n";

   // Undefined variable error displayed
   echo $undefinedVariable;

   // Turn off error reporting
   error_reporting(0);
   echo "Error reporting is now turned off.\n";

   // Another undefined variable (no error displayed)
   echo $anotherUndefinedVariable;
?> 

Output

This will create the below output −

All errors are currently displayed.
Notice: Undefined variable: undefinedVariable in /path/to/your/script.php on line X
Error reporting is now turned off.