在实际开发中，错误及异常捕捉仅仅靠try{}catch()是远远不够的。
所以引用以下几中函数。
a)   set_error_handler
一般用于捕捉  E_NOTICE 、E_USER_ERROR、E_USER_WARNING、E_USER_NOTICE
不能捕捉：
E_ERROR, E_PARSE, E_CORE_ERROR, E_CORE_WARNING, E_COMPILE_ERROR and E_COMPILE_WARNING。
一般与trigger_error("...", E_USER_ERROR)，配合使用。

<?php// we will do our own error handlingerror_reporting(0);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";	echo $err;}function distance($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_handle = set_error_handler("userErrorHandler");$t = I_AM_NOT_DEFINED;	//generates a warning// define some "vectors"$a = array(2, 3, "foo");$b = array(5.5, 4.3, -1.6);$c = array(1, -3);//generate a user error$t1 = distance($c,$b);// generate another user error$t2 = distance($b, "i am not an array") . "\n";// generate a warning$t3 = distance($a, $b) . "\n";?>

b)   set_exception_handler
设置默认的异常处理程序，用于没有用 try/catch 块来捕获的异常。 在 exception_handler 调用后异常会中止。
与throw new Exception(‘Uncaught Exception occurred‘)，连用。

<?php// we will do our own error handlingerror_reporting(0);function exceptHandle($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    	$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 (1) {        		$err .= "\t<vartrace>" . wddx_serialize_value($vars, "Variables") . "</vartrace>\n";    	}    	$err .= "</errorentry>\n\n";	echo $err;}$old_except_handle = set_exception_handler("exceptHandle");//$t = I_AM_NOT_DEFINED;	//generates a warning$a;throw new Exception(‘Uncaught Exception occurred‘);    ?>

c)   register_shutdown_function
执行机制是：php把要调用的函数调入内存。当页面所有ＰＨＰ语句都执行完成时，再调用此函数。
一般与trigger_error("...", E_USER_ERROR)，配合使用。

<?phperror_reporting(0);date_default_timezone_set(‘Asia/Shanghai‘);register_shutdown_function(‘my_exception_handler‘);$t = I_AM_NOT_DEFINED;	//generates a warningtrigger_error("Vectors need to be of the same size", E_USER_ERROR);     function my_exception_handler(){    if($e = error_get_last()) {    //$e[‘type‘]对应php_error常量    $message = ‘‘;    $message .= "出错信息:\t".$e[‘message‘]."\n\n";    $message .= "出错文件:\t".$e[‘file‘]."\n\n";    $message .= "出错行数:\t".$e[‘line‘]."\n\n";    $message .= "\t\t请工程师检查出现程序".$e[‘file‘]."出现错误的原因\n";    $message .= "\t\t希望能您早点解决故障出现的原因<br/>";	echo $message;    //sendemail to    }}?>

定义和用法 restore_error_handler() 函数恢复之前的错误处理程序，该程序是由 set_error_handler() 函数改变的。

该函数永远返回 true。

是 set_error_handler()的反函数。

php错误及异常捕捉