For syntax errors, you need to enable error display in the php.ini. By default these are turned off because you don't want a "customer" seeing the error messages. Check this page in the PHP documentation for information on the 2 directives: error_reporting
and display_errors
. display_errors
is probably the one you want to change. If you can't modify the php.ini, you can also add the following lines to an .htaccess file:
php_flag display_errors on
php_value error_reporting 2039
You may want to consider using the value of E_ALL (as mentioned by Gumbo) for your version of PHP for error_reporting
to get all of the errors. more info
3 other items: (1) You can check the error log file as it will have all of the errors (unless logging has been disabled). (2) Adding the following 2 lines will help you debug errors that are not syntax errors:
error_reporting(-1);
ini_set('display_errors', 'On');
(3) Another option is to use an editor that checks for errors when you type, such as PhpEd. PhpEd also comes with a debugger which can provide more detailed information. (The PhpEd debugger is very similar to xdebug and integrates directly into the editor so you use 1 program to do everything.)
Cartman's link is also very good: http://www.ibm.com/developerworks/library/os-debug/
Update: This is not a catchable fatal error anymore in php 7. Instead an "exception" is thrown. An "exception" (in scare quotes) that is not derived from Exception but Error; it's still a Throwable and can be handled with a normal try-catch block. see https://wiki.php.net/rfc/throwable-interface
E.g.
<?php
class ClassA {
public function method_a (ClassB $b) { echo 'method_a: ', get_class($b), PHP_EOL; }
}
class ClassWrong{}
class ClassB{}
class ClassC extends ClassB {}
foreach( array('ClassA', 'ClassWrong', 'ClassB', 'ClassC') as $cn ) {
try{
$a = new ClassA;
$a->method_a(new $cn);
}
catch(Error $err) {
echo "catched: ", $err->getMessage(), PHP_EOL;
}
}
echo 'done.';
prints
catched: Argument 1 passed to ClassA::method_a() must be an instance of ClassB, instance of ClassA given, called in [...]
catched: Argument 1 passed to ClassA::method_a() must be an instance of ClassB, instance of ClassWrong given, called in [...]
method_a: ClassB
method_a: ClassC
done.
Old answer for pre-php7 versions:
http://docs.php.net/errorfunc.constants says:
E_RECOVERABLE_ERROR ( integer )
Catchable fatal error. It indicates that a probably dangerous error occured, but did not leave the Engine in an unstable state. If the error is not caught by a user defined handle (see also set_error_handler()), the application aborts as it was an E_ERROR.
see also: http://derickrethans.nl/erecoverableerror.html
e.g.
function myErrorHandler($errno, $errstr, $errfile, $errline) {
if ( E_RECOVERABLE_ERROR===$errno ) {
echo "'catched' catchable fatal error\n";
return true;
}
return false;
}
set_error_handler('myErrorHandler');
class ClassA {
public function method_a (ClassB $b) {}
}
class ClassWrong{}
$a = new ClassA;
$a->method_a(new ClassWrong);
echo 'done.';
prints
'catched' catchable fatal error
done.
edit: But you can "make" it an exception you can handle with a try-catch block
function myErrorHandler($errno, $errstr, $errfile, $errline) {
if ( E_RECOVERABLE_ERROR===$errno ) {
echo "'catched' catchable fatal error\n";
throw new ErrorException($errstr, $errno, 0, $errfile, $errline);
// return true;
}
return false;
}
set_error_handler('myErrorHandler');
class ClassA {
public function method_a (ClassB $b) {}
}
class ClassWrong{}
try{
$a = new ClassA;
$a->method_a(new ClassWrong);
}
catch(Exception $ex) {
echo "catched\n";
}
echo 'done.';
see: http://docs.php.net/ErrorException
Best Answer
PHP 7.1 or newer (released 2nd December 2016)
You can explicitly declare a variable to be
null
with this syntaxthis will result in
So, if you want an optional argument you can follow the convention
Type $t = null
whereas if you need to make an argument accept bothnull
and its type, you can follow above example.You can read more here.
PHP 7.0 or older
You have to add a default value like
That way, you can pass it a null value.
This is documented in the section in the manual about Type Declarations: