(PHP 4 >= 4.0.1, PHP 5)
set_error_handler — Sets a user-defined error handler function
Sets a user function (error_handler) to handle
errors in a script.
This function can be used for defining your own way of handling errors during runtime, for example in applications in which you need to do cleanup of data/files when a critical error happens, or when you need to trigger an error under 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_types
unless the callback function returns FALSE.
error_reporting() settings will have no effect and your
error handler will be called regardless - however you are still able to read
the current value of
error_reporting and act
appropriately. Of particular note is that this value will be 0 if the
statement that caused the error was prepended by the
@ error-control
operator.
Also note that it is your responsibility to die() if necessary. 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, 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.
error_handler
A callback with the following signature.
NULL may be passed instead, to reset this handler to its default state.
$errno
, string $errstr
[, string $errfile
[, int $errline
[, array $errcontext
]]] )errnoerrno, contains the
level of the error raised, as an integer.
errstrerrstr, contains the
error message, as a string.
errfileerrfile,
which contains the filename that the error was raised in, as a string.
errlineerrline,
which contains the line number the error was raised at, as an integer.
errcontexterrcontext,
which is 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 handler must not modify error context.
If the function returns FALSE then the normal error handler continues.
error_types
Can be used to mask the triggering of the
error_handler function just like the error_reporting ini setting
controls which errors are shown. Without this mask set the
error_handler will be called for every error
regardless to the setting of the error_reporting setting.
Returns a string containing the previously defined error handler (if any). If
the built-in error handler is used NULL is returned. NULL is also returned
in case of an error such as an invalid callback. If the previous error handler
was a class method, this function will return an indexed array with the class
and the method name.
| Version | Description |
|---|---|
| 5.5.0 |
error_handler now accepts NULL.
|
| 5.2.0 |
The error handler must return FALSE to populate
$php_errormsg.
|
| 5.0.0 |
The error_types parameter was introduced.
|
| 4.3.0 |
Instead of a function name, an array containing an object reference
and a method name can also be supplied as the
error_handler.
|
| 4.0.2 |
Three optional parameters for the error_handler
user function was introduced. These are the filename, the line number,
and the context.
|
Example #1 Error handling with set_error_handler() and trigger_error()
The example below shows the handling of internal exceptions by triggering errors and handling them with a user defined function:
<?php
// error handler function
function myErrorHandler($errno, $errstr, $errfile, $errline)
{
if (!(error_reporting() & $errno)) {
// This error code is not included in error_reporting
return;
}
switch ($errno) {
case E_USER_ERROR:
echo "<b>My ERROR</b> [$errno] $errstr<br />\n";
echo " Fatal error on line $errline in file $errfile";
echo ", PHP " . PHP_VERSION . " (" . PHP_OS . ")<br />\n";
echo "Aborting...<br />\n";
exit(1);
break;
case E_USER_WARNING:
echo "<b>My WARNING</b> [$errno] $errstr<br />\n";
break;
case E_USER_NOTICE:
echo "<b>My NOTICE</b> [$errno] $errstr<br />\n";
break;
default:
echo "Unknown error type: [$errno] $errstr<br />\n";
break;
}
/* Don't execute PHP internal error handler */
return true;
}
// function to test the error handling
function scale_by_log($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 to the user defined error handler
$old_error_handler = set_error_handler("myErrorHandler");
// trigger some errors, first define a mixed array with a non-numeric item
echo "vector a\n";
$a = array(2, 3, "foo", 5.5, 43.3, 21.11);
print_r($a);
// now generate second array
echo "----\nvector b - a notice (b = log(PI) * a)\n";
/* Value at position $pos is not a number, using 0 (zero) */
$b = scale_by_log($a, M_PI);
print_r($b);
// this is trouble, we pass a string instead of an array
echo "----\nvector c - a warning\n";
/* Incorrect input vector, array of values expected */
$c = scale_by_log("not array", 2.3);
var_dump($c); // NULL
// this is a critical error, log of zero or negative number is undefined
echo "----\nvector d - fatal error\n";
/* log(x) for x <= 0 is undefined, you used: scale = $scale" */
$d = scale_by_log($a, -2.5);
var_dump($d); // Never reached
?>
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 />