PHP Custom Error Handling

Creating a Custom Error Handler

Creating a custom error handler is quite simple. We simply create a special function that can be called when an error occurs in PHP.

This function must be able to handle a minimum of two parameters (error level and error message) but can accept up to five parameters (optionally: file, line-number, and the error context):

 Syntax

error_function(error_level,error_message,error_file,error_line,error_context)

Parameter	Description
error_level	Required. Specifies the error report level for the user-defined error. Must be a value number. See table below for possible error report levels
error_message	Required. Specifies the error message for the user-defined error
error_file	Optional. Specifies the filename in which the error occurred
error_line	Optional. Specifies the line number in which the error occurred
error_context	Optional. Specifies an array containing every variable, and their values, in use when the error occurred

Error Report levels

These error report levels are the different types of error the user-defined error handler can be used for:

Value	Constant	Description
2	E_WARNING	Non-fatal run-time errors. Execution of the script is not halted
8	E_NOTICE	Run-time notices. The script found something that might be an error, but could also happen when running a script normally
256	E_USER_ERROR	Fatal user-generated error. This is like an E_ERROR set by the programmer using the PHP function trigger_error()
512	E_USER_WARNING	Non-fatal user-generated warning. This is like an E_WARNING set by the programmer using the PHP function trigger_error()
1024	E_USER_NOTICE	User-generated notice. This is like an E_NOTICE set by the programmer using the PHP function trigger_error()
4096	E_RECOVERABLE_ERROR	Catchable fatal error. This is like an E_ERROR but can be caught by a user defined handle (see also set_error_handler())
8191	E_ALL	All errors and warnings (E_STRICT became a part of E_ALL in PHP 5.4)

Now lets create a function to handle errors:

<?php
error_reporting(E_ALL);

function myErrorHandler($errorNo, $errorStr, $errFile, $errLine) {
    switch ($errorNo) {
        case E_USER_ERROR:
            echo '<BR>E_USER_ERROR';
            echo "<BR>Error no: ".$errorNo;
            echo "<BR>Error str: ".$errorStr;
            echo "<BR>Error file: ".$errFile;
            echo "<BR>Error line: ".$errLine;
            break;
        case E_WARNING:
        case E_USER_WARNING:
            echo '<BR>E_WARNING, E_USER_WARNING';
            echo "<BR>Error no: ".$errorNo;
            echo "<BR>Error str: ".$errorStr;
            echo "<BR>Error file: ".$errFile;
            echo "<BR>Error line: ".$errLine;
            break;
        case E_NOTICE:
        case E_USER_NOTICE:
            echo '<BR>E_NOTICE, E_USER_NOTICE';
            echo "<BR>Error no: ".$errorNo;
            echo "<BR>Error str: ".$errorStr;
            echo "<BR>Error file: ".$errFile;
            echo "<BR>Error line: ".$errLine;
            break;
        default :
            echo '<BR>default';
            echo "<BR>Error no: ".$errorNo;
            echo "<BR>Error str: ".$errorStr;
            echo "<BR>Error file: ".$errFile;
            echo "<BR>Error line: ".$errLine;
            break;
    }
    echo "<BR>";

    /* Don't execute PHP internal error handler */

    return true;
}
set_error_handler("myErrorHandler");

$x = $y + 3;

$f = fopen("a.txt", "r");
?>

And output would be like:

E_NOTICE, E_USER_NOTICE
Error no: 8
Error str: Undefined variable: y
Error file: C:\xampp\htdocs\index.php
Error line: 42

E_WARNING, E_USER_WARNING
Error no: 2
Error str: fopen(a.txt) [function.fopen]: failed to open stream: No such file or directory
Error file: C:\xampp\htdocs\index.php
Error line: 44