set_error_handler

    (PHP 4 >= 4.0.1, PHP 5, PHP 7, PHP 8)

    set_error_handler — Sets a user-defined error handler function

    Description

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

    Sets a user function (callback) to handle errors in a script.

    This function can be used to define custom error handlers during runtime, for example in applications which need to do file/data cleanup when a critical error happens, or when triggering an error in response to certain conditions (using trigger_error()).

    It is important to remember that the standard PHP error handler is completely bypassed for the error types specified by error_levels unless the callback function returns false. error_reporting() settings will have no effect and the error handler will be called regardless - however, it's still possible to read the current value of error_reporting and act appropriately.

    Also note that it is the handler's responsibility to stop the script's execution if necessary by calling exit(). If the error-handler function returns, script execution will continue with the next statement after the one that caused an error.

    The following error types cannot be handled with a user defined function: E_ERROR, E_PARSE, E_CORE_ERROR, E_CORE_WARNING, E_COMPILE_ERROR, E_COMPILE_WARNING independent of where they were raised, and most of E_STRICT raised in the file where set_error_handler() is called.

    If errors occur before the script is executed (e.g. on file uploads) the custom error handler cannot be called since it is not registered at that time.

    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 = ?,
        array$errcontext = ?
    ): bool
    errno
    The first parameter, errno, will be passed the level of the error raised, as an integer.
    errstr
    The second parameter, errstr, will be passed the error message, as a string.
    errfile
    If the callback accepts a third parameter, errfile, it will be passed the filename that the error was raised in, as a string.
    errline
    If the callback accepts a fourth parameter, errline, it will be passed the line number where the error was raised, as an integer.
    errcontext
    If the callback accepts a fifth parameter, errcontext, it will be passed an array that points to the active symbol table at the point the error occurred. In other words, errcontext will contain an array of every variable that existed in the scope the error was triggered in. User error handlers must not modify the error context.
    Warning

    This parameter has been DEPRECATED as of PHP 7.2.0, and REMOVED as of PHP 8.0.0. If the function defines this parameter without a default, an error of "too few arguments" will be raised when it is called.

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

    error_levels

    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.

    Return Values

    Returns the previously defined error handler (if any). If the built-in error handler is used null is returned. If the previous error handler was a class method, this function will return an indexed array with the class and the method name.

    Changelog

    VersionDescription
    8.0.0errcontext was removed, and will no longer be passed to user callbacks.
    7.2.0errcontext became deprecated. Usage of this parameter now emits an E_DEPRECATED notice.

    Examples

    Example #1 Error handling with set_error_handler() and trigger_error()

    The example below shows the handling of internal exceptions by triggering errors and handling them with a user defined function:

    <?php
    // error handler function
    function myErrorHandler($errno, $errstr, $errfile, $errline)
    {
    if (!(    error_reporting() & $errno)) {
    // This error code is not included in error_reporting, so let it fall

    The above example will output something similar to:

    vector a Array ( [0] => 2 [1] => 3 [2] => foo [3] => 5.5 [4] => 43.3 [5] => 21.11 ) ---- vector b - a notice (b = log(PI) * a) <b>My NOTICE</b> [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 ) ---- vector c - a warning <b>My WARNING</b> [512] Incorrect input vector, array of values expected<br /> NULL ---- vector d - fatal error <b>My ERROR</b> [256] log(x) for x <= 0 is undefined, you used: scale = -2.5<br /> Fatal error on line 35 in file trigger_error.php, PHP 5.2.1 (FreeBSD)<br /> Aborting...<br />

    See Also

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