set_error_handler

Description

Sets a user function (error_handler) to handle errors in a script_ Returns the previously defined error handler (if any), or FALSE on error_ 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())

The user function needs to accept 2 parameters: the error code, and a string describing the error_ The example below shows the handling of internal execptions by triggering errors and handling them with a user defined function:

Ejemplo 1_ Error handling with set_error_handler() and trigger_error() <?php // redefine the user error constants _ PHP4 only define (FATAL,E_USER_ERROR); define (ERROR,E_USER_WARNING); define (WARNING,E_USER_NOTICE); // set the error reporting level for this script error_reporting (FATAL + ERROR + WARNING); // error handler function function myErrorHandler ($errno, $errstr) { switch ($errno) { case FATAL: echo "<b>FATAL</b> [$errno] $errstr<br>\n"; echo " Fatal error in line "___LINE___" of file "___FILE__; echo ", PHP "_PHP_VERSION_" ("_PHP_OS_")<br>\n"; echo "Aborting___<br>\n"; exit _1; break; case ERROR: echo "<b>ERROR</b> [$errno] $errstr<br>\n"; break; case WARNING: echo "<b>WARNING</b> [$errno] $errstr<br>\n"; break; default: echo "Unkown error type: [$errno] $errstr<br>\n"; break; } } // function to test the error handling function scale_by_log ($vect, $scale) { if ( !is_numeric($scale) || $scale <= 0 ) trigger_error("log(x) for x <= 0 is undefined, you used: scale = $scale", FATAL); if (!is_array($vect)) { trigger_error("Incorrect input vector, array of values expected", ERROR); return null; } for ($i=0; $i<count($vect); $i++) { if (!is_numeric($vect[$i])) trigger_error("Value at position $i is not a number, using 0 (zero)", WARNING); $temp[$i] = log($scale) * $vect[$i]; } 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, generating a warning echo "____\nvector b _ a warning (b = log(PI) * a)\n"; $b = scale_by_log($a, M_PI); print_r($b); // this is trouble, we pass a string instead of an array echo "____\nvector c _ an error\n"; $c = scale_by_log("not array",2_3); var_dump($c); // this is a critical error, log of zero or negative number is undefined echo "____\nvector d _ fatal error\n"; $d = scale_by_log($a, _2_5); ?>

And when you run this sample script, the output will be

vector a
Array
(
    [0] => 2
    [1] => 3
    [2] => foo
    [3] => 5_5
    [4] => 43_3
    [5] => 21_11
)
____
vector b _ a warning (b = log(PI) * a)
<b>WARNING</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 _ an error
<b>ERROR</b> [512] Incorrect input vector, array of values expected<br>
NULL
____
vector d _ fatal error
<b>FATAL</b> [256] log(x) for x <= 0 is undefined, you used: scale = _2_5<br>
  Fatal error in line 16 of file trigger_error_php, PHP 4_0_1pl2 (Linux)<br>
Aborting___<br>

See also error_reporting(), restore_error_handler(), trigger_error(), user_error()