Examples

Below we can see an example of using the error handling capabilities in PHP. We define an error handling function which logs the information into a file (using an XML format), and e-mails the developer in case a critical error in the logic happens.
Example #1 Using error handling in a script

<?php

// we will do our own error handling

error_reporting(0);



// user defined error handling function

function userErrorHandler($errno, $errmsg, $filename, $linenum, $vars) 

{

    // timestamp for the error entry

    $dt = date("Y-m-d H:i:s (T)");



    // define an assoc array of error string

    // in reality the only entries we should

    // consider are E_WARNING, E_NOTICE, E_USER_ERROR,

    // E_USER_WARNING and E_USER_NOTICE

    $errortype = array (

                E_ERROR              => 'Error',

                E_WARNING            => 'Warning',

                E_PARSE              => 'Parsing Error',

                E_NOTICE             => 'Notice',

                E_CORE_ERROR         => 'Core Error',

                E_CORE_WARNING       => 'Core Warning',

                E_COMPILE_ERROR      => 'Compile Error',

                E_COMPILE_WARNING    => 'Compile Warning',

                E_USER_ERROR         => 'User Error',

                E_USER_WARNING       => 'User Warning',

                E_USER_NOTICE        => 'User Notice',

                E_STRICT             => 'Runtime Notice',

                E_RECOVERABLE_ERROR  => 'Catchable Fatal Error'

                );

    // set of errors for which a var trace will be saved

    $user_errors = array(E_USER_ERROR, E_USER_WARNING, E_USER_NOTICE);

    

    $err = "<errorentry>\n";

    $err .= "\t<datetime>" . $dt . "</datetime>\n";

    $err .= "\t<errornum>" . $errno . "</errornum>\n";

    $err .= "\t<errortype>" . $errortype[$errno] . "</errortype>\n";

    $err .= "\t<errormsg>" . $errmsg . "</errormsg>\n";

    $err .= "\t<scriptname>" . $filename . "</scriptname>\n";

    $err .= "\t<scriptlinenum>" . $linenum . "</scriptlinenum>\n";



    if (in_array($errno, $user_errors)) {

        $err .= "\t<vartrace>" . wddx_serialize_value($vars, "Variables") . "</vartrace>\n";

    }

    $err .= "</errorentry>\n\n";

    

    // for testing

    // echo $err;



    // save to the error log, and e-mail me if there is a critical user error

    error_log($err, 3, "/usr/local/php4/error.log");

    if ($errno == E_USER_ERROR) {

        mail("phpdev@example.com", "Critical User Error", $err);

    }

}





function distance($vect1, $vect2) 

{

    if (!is_array($vect1) || !is_array($vect2)) {

        trigger_error("Incorrect parameters, arrays expected", E_USER_ERROR);

        return NULL;

    }



    if (count($vect1) != count($vect2)) {

        trigger_error("Vectors need to be of the same size", E_USER_ERROR);

        return NULL;

    }



    for ($i=0; $i<count($vect1); $i++) {

        $c1 = $vect1[$i]; $c2 = $vect2[$i];

        $d = 0.0;

        if (!is_numeric($c1)) {

            trigger_error("Coordinate $i in vector 1 is not a number, using zero", 

                            E_USER_WARNING);

            $c1 = 0.0;

        }

        if (!is_numeric($c2)) {

            trigger_error("Coordinate $i in vector 2 is not a number, using zero", 

                            E_USER_WARNING);

            $c2 = 0.0;

        }

        $d += $c2*$c2 - $c1*$c1;

    }

    return sqrt($d);

}



$old_error_handler = set_error_handler("userErrorHandler");



// undefined constant, generates a warning

$t = I_AM_NOT_DEFINED;



// define some "vectors"

$a = array(2, 3, "foo");

$b = array(5.5, 4.3, -1.6);

$c = array(1, -3);



// generate a user error

$t1 = distance($c, $b) . "\n";



// generate another user error

$t2 = distance($b, "i am not an array") . "\n";



// generate a warning

$t3 = distance($a, $b) . "\n";



?>