XXVII. Error Handling and Logging Functions

Introduction

These are functions dealing with error handling and logging. They allow you to define your own error handling rules, as well as modify the way the errors can be logged. This allows you to change and enhance error reporting to suit your needs.

With the logging functions, you can send messages directly to other machines, to an email (or email to pager gateway!), to system logs, etc., so you can selectively log and monitor the most important parts of your applications and websites.

The error reporting functions allow you to customize what level and kind of error feedback is given, ranging from simple notices to customized functions returned during errors.

Requirements

These functions are available as part of the standard module, which is always available.

Installation

There is no installation needed to use these functions, they are part of the PHP core.

Predefined Constants

These constants are part of the PHP core and always available. 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.

Table 1. Errors and Logging

ValueConstantDescription
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.
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. PHP 4 only.
64 E_COMPILE_ERROR (integer) Fatal compile-time errors. This is like an E_ERROR, except it is generated by the Zend Scripting Engine. PHP 4 only.
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. PHP 4 only.
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(). PHP 4 only.
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(). PHP 4 only.
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(). PHP 4 only.
2047 E_ALL (integer) All errors and warnings, as supported.

See Also

Fore more Information see the section Error Handling.

Table of Contents
error_log -- send an error message somewhere
error_reporting -- set which PHP errors are reported
restore_error_handler --  Restores the previous error handler function
set_error_handler --  Sets a user-defined error handler function.
trigger_error --  Generates a user-level error/warning/notice message
user_error --  Generates a user-level error/warning/notice message