1. Errors

2. Fatal Errors
Calling undefined functions
require() when the file does not exist

3. Fatal Errors - example
<?php
//call a non-existent function
test_function();
?>
Output
Fatal error: Call to undefined function test_function() in
/var/www/website/html/index.php on line 4

4. Warnings and Notices
Undefined variables
Referencing non-existent array keys
Typos
Wrong variable types passed to functions

5. Warnings and Notices -
Example
<?php
//initialise the string variable
$string = ‘a string’;
//explode() a string
explode($string); ?>
Output:
Warning: Wrong parameter count for explode() in
/var/www/website.com/html/index.php on line 6

6. Database Errors
Can’t connect to a database
Can’t access a table
Broken query

7. Fatal Errors
Usually displays a blank page
Error messages are hidden from users, but
are logged

8. Warnings and Notices
Page will display, but may stop executing
prematurely
Error messages are hidden from the user,
but are logged
Affects performance & user experience

9. Database Errors
If the database can’t connect, it returns a
fatal error
If a table/field can’t or found, or a query can’t
be executed, it returns a warning

10. Better Error Handling
Define a custom error handler:
set_error_handler(‘function_name’);
Accept five arguments:-
• error type
• message
• file name
• line number
• context

11. Better Error Handling -
continued
Do whatever you want to within the function
– Output a message to the user
– Send an email to someone dependent on the
error
Errors are still logged
Should be built into base systems
Does not work for a fatal error.

12. Better Error Handling -
continued
register_shutdown_function()
This function will be called once a fatal error
has happened
However, it is executed after PHP has
finished processing every single script
Be careful with it!