set_error_handler

Description
Syntax
Examples
Links

Description

The set_error_handler of Error Handling for PHP sets a user-defined error handler function.

Syntax

set_error_handler(
    ?callable $callback,
    int $error_levels = E_ALL
): ?callable

Parameters

callback

If null is passed, the handler is reset to its default state. Otherwise, the handler is a callback with the following signature:

handler(
    int $errno,
    string $errstr,
    string $errfile = ?,
    int $errline = ?
): bool

errno

The first parameter, errno, contains the level of the error raised, as an integer.

errstr

The second parameter, errstr, contains the error message, as a string.

errfile

The third parameter is optional, errfile, which contains the filename that the error was raised in, as a string.

errline

The fourth parameter is optional, errline, which contains the line number the error was raised at, as an integer.

If the function returns false then the normal error handler continues.

Can be used to mask the triggering of the callback function just like the error_reporting ini setting controls which errors are shown. Without this mask set the callback will be called for every error regardless to the setting of the error_reporting setting.

<?

function myErrorHandler($errno, $errstr, $errfile, $errline)
{
    if (!(error_reporting() & $errno)) {
        // This error code is not included in error_reporting, so let it fall through to the standard PHP error handler
        return false;
    }

    switch ($errno) {
        case E_USER_ERROR:
            echo "ERROR [$errno] $errstr<br>\n";
            echo "os: " . PHP_OS . "<br>\nversion: " . PHP_VERSION . "<br>\nfile: $errfile<br>\nline: $errline<br>\n";
            exit(1);
            break;
        case E_USER_WARNING:
            echo "WARNING [$errno] $errstr<br>\n";
            break;
        case E_USER_NOTICE:
            echo "NOTICE [$errno] $errstr<br>\n";
            break;
        default:
            echo "UNKNOWN [$errno] $errstr<br>\n";
            break;
    }

    // Don't execute PHP internal error handler
    return true;
}

function scaleByLog($vect, $scale)
{
    if (!is_numeric($scale) || $scale <= 0) {
        trigger_error("log(x) for x <= 0 is undefined, you used: scale = $scale", E_USER_ERROR);
    }

    if (!is_array($vect)) {
        trigger_error("Incorrect input vector, array of values expected", E_USER_WARNING);
        return null;
    }

    $temp = array();
    foreach($vect as $pos => $value) {
        if (!is_numeric($value)) {
            trigger_error("Value at position $pos is not a number, using 0 (zero)", E_USER_NOTICE);
            $value = 0;
        }
        $temp[$pos] = log($scale) * $value;
    }

    return $temp;
}

// set the user defined error handler
set_error_handler("myErrorHandler");

// define a mixed array with a non-numeric item
$a = array(2, 3, "test", 5.5, 43.3, 21.11);
print_r($a);

// NOTICE Value at position $pos is not a number, using 0 (zero)
$b = scaleByLog($a, M_PI);
print_r($b);

// WARNING Incorrect input vector, array of values expected
$c = scaleByLog("not array", 2.3);
print_r($c); // NULL

// ERROR log(x) for x <= 0 is undefined, you used: scale = $scale
$d = scaleByLog($a, -2.5);
print_r($d); // Never reached

Array
(
    [0] => 2
    [1] => 3
    [2] => test
    [3] => 5.5
    [4] => 43.3
    [5] => 21.11
)
NOTICE [1024] Value at position 2 is not a number, using 0 (zero)<br>
Array
(
    [0] => 2.2894597716988
    [1] => 3.4341896575482
    [2] => 0
    [3] => 6.2960143721717
    [4] => 49.566804057279
    [5] => 24.165247890281
)
WARNING [512] Incorrect input vector, array of values expected<br>
ERROR [256] log(x) for x <= 0 is undefined, you used: scale = -2.5<br>
os: Linux<br>
version: 8.3.12<br>
file: file.php<br>
line: 34<br>