Predefined Constants

The constants below are always available as part of the PHP core.

Note: You may use these constant names in php.ini but not outside of PHP, like in httpd.conf, where you'd use the bitmask values instead.

**Errors and Logging**
Value	Constant	Description	Note
1	`E_ERROR` (integer)	Fatal run-time errors. These indicate errors that can not be recovered from, such as a memory allocation problem. Execution of the script is halted.
2	`E_WARNING` (integer)	Run-time warnings (non-fatal errors). Execution of the script is not halted.
4	`E_PARSE` (integer)	Compile-time parse errors. Parse errors should only be generated by the parser.
8	`E_NOTICE` (integer)	Run-time notices. Indicate that the script encountered something that could indicate an error, but could also happen in the normal course of running a script.
16	`E_CORE_ERROR` (integer)	Fatal errors that occur during PHP's initial startup. This is like an `E_ERROR`, except it is generated by the core of PHP.	since PHP 4
32	`E_CORE_WARNING` (integer)	Warnings (non-fatal errors) that occur during PHP's initial startup. This is like an `E_WARNING`, except it is generated by the core of PHP.	since PHP 4
64	`E_COMPILE_ERROR` (integer)	Fatal compile-time errors. This is like an `E_ERROR`, except it is generated by the Zend Scripting Engine.	since PHP 4
128	`E_COMPILE_WARNING` (integer)	Compile-time warnings (non-fatal errors). This is like an `E_WARNING`, except it is generated by the Zend Scripting Engine.	since PHP 4
256	`E_USER_ERROR` (integer)	User-generated error message. This is like an `E_ERROR`, except it is generated in PHP code by using the PHP function trigger_error().	since PHP 4
512	`E_USER_WARNING` (integer)	User-generated warning message. This is like an `E_WARNING`, except it is generated in PHP code by using the PHP function trigger_error().	since PHP 4
1024	`E_USER_NOTICE` (integer)	User-generated notice message. This is like an `E_NOTICE`, except it is generated in PHP code by using the PHP function trigger_error().	since PHP 4
2048	`E_STRICT` (integer)	Run-time notices. Enable to have PHP suggest changes to your code which will ensure the best interoperability and forward compatibility of your code.	since PHP 5
4096	`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`.	since PHP 5.2.0
8191	`E_ALL` (integer)	All errors and warnings, as supported, except of level `E_STRICT` in PHP < 6.	6143 in PHP 5.2.x and 2047 previously

The above values (either numerical or symbolic) are used to build up a bitmask that specifies which errors to report. You can use the bitwise operators to combine these values or mask out certain types of errors. Note that only '|', '~', '!', '^' and '&' will be understood within php.ini.