PHP Error and Logging Functions

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# PHP Error and Logging Functions

## PHP Error and Logging Introduction

The error and logging functions allows error handling and logging.

The error functions allow users to define error handling rules, and modify the way the errors can be logged.

The logging functions allow users to log applications and send log messages to email, system logs or other machines.

## Installation

The error and logging functions are part of the PHP core. There is no installation needed to use these functions.

## PHP Error and Logging Functions

PHP: indicates the earliest version of PHP that supports the function.

Function | Description | PHP
--- | --- | ---
debug_backtrace() | Generates a backtrace | 4
debug_print_backtrace() | Prints a backtrace | 5
error_get_last() | Gets the last error occurred | 5
error_log() | Sends an error to the server error-log, to a file or to a remote destination | 4
error_reporting() | Specifies which errors are reported | 4
restore_error_handler() | Restores the previous error handler | 4
restore_exception_handler() | Restores the previous exception handler | 5
set_error_handler() | Sets a user-defined function to handle errors | 4
set_exception_handler() | Sets a user-defined function to handle exceptions | 5
trigger_error() | Creates a user-defined error message | 4
user_error() | Alias of trigger_error() | 4

## PHP Error and Logging Constants

PHP: indicates the earliest version of PHP that supports the constant.

Value | Constant | Description | PHP
--- | --- | --- | ---
1 | E_ERROR | Fatal run-time errors. Errors that cannot be recovered from. Execution of the script is halted |
2 | E_WARNING | Non-fatal run-time errors. Execution of the script is not halted |
4 | E_PARSE | Compile-time parse errors. Parse errors should only be generated by the parser |
8 | E_NOTICE | Run-time notices. The script found something that might be an error, but could also happen when running a script normally |
16 | E_CORE_ERROR | Fatal errors at PHP startup. This is like an E_ERROR in the PHP core | 4
32 | E_CORE_WARNING | Non-fatal errors at PHP startup. This is like an E_WARNING in the PHP core | 4
64 | E_COMPILE_ERROR | Fatal compile-time errors. This is like an E_ERROR generated by the Zend Scripting Engine | 4
128 | E_COMPILE_WARNING | Non-fatal compile-time errors. This is like an E_WARNING generated by the Zend Scripting Engine | 4
256 | E_USER_ERROR | Fatal user-generated error. This is like an E_ERROR set by the programmer using the PHP function trigger_error() | 4
512 | E_USER_WARNING | Non-fatal user-generated warning. This is like an E_WARNING set by the programmer using the PHP function trigger_error() | 4
1024 | E_USER_NOTICE | User-generated notice. This is like an E_NOTICE set by the programmer using the PHP function trigger_error() | 4
2048 | E_STRICT | Run-time notices. PHP suggest changes to your code to help interoperability and compatibility of the code | 5
4096 | E_RECOVERABLE_ERROR | Catchable fatal error. This is like an E_ERROR but can be caught by a user defined handle (see also set_error_handler()) | 5
8191 | E_ALL | All errors and warnings, except of level E_STRICT | 5

From http://www.w3schools.com (Copyright Refsnes Data)