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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 if 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_ERRORE_USER_WARNINGE_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($err3"/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(23"foo");
$b = array(5.54.3, -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";

?>



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