The document outlines the structure and functionality of PHP arrays, including multidimensional and superglobal arrays, which are always in scope for easy access. It explains error and exception handling in PHP, categorizing errors into expected errors, warnings, and fatal errors, and discusses error reporting settings and mechanisms for handling runtime errors. Additionally, it touches upon custom exception handlers to improve user experience and provide relevant application information during errors.

1. PHP Arrays & Classes
Developed by
Mr.V.Sivakumar

2. PHP Arrays
• In general, an array is a data structure that allows the
programmer to collect a number of related elements
together in a single variable.
• Unlike most other programming languages, in PHP an
array is actually an ordered map, which associates each
value in the array with a key.
• PHP array is not only like other languages arrays, but it
is also like their vector, hash table, dictionary, and list
collections.

5. Multidimensional arrays

6. Multidimensional arrays

7. superglobal arrays
• PHP uses special predefined associative arrays called superglobal variables
that allow the programmer to easily access HTTP headers, query string
parameters.
• They are called superglobal because these arrays are always in scope and
always exist, ready for the programmer to access or modify them without
having to use the global keyword.

9. Errors and Exceptions
• A failure in any one of these systems will mean that the web application
will no longer run successfully.
• Types of errors
■ Expected errors
■ Warnings
■ Fatal errors
• An expected error is an error that routinely occurs during an application.
An error as a result of user inputs, for instance, entering letters when
numbers were expected.
• Users will leave fields blank, enter text when numbers were expected, type
in too much or too little text, forget to click certain things.

10. Errors and Exceptions
• Warnings, that generate a PHP warning message (which may or may
not be displayed) but will not halt the execution of the page. For
instance, calling a function without a required parameter will
generate a warning but not stop execution.
• Fatal errors, which are serious in that the execution of the page will
terminate unless handled in some way. These should truly be
exceptional and unexpected, such as a required input file being
missing or a database table or field disappearing.

11. PHP Error reporting
• There are three main error reporting flags:
■ error_reporting
■ display_errors
■ log_errors
• The error_reporting setting specifies which type of errors are to be
reported
error_reporting = E_ALL / E_ERROR / E_WARNING
• display_error setting specifies whether error messages should or
should not be displayed in the browser.
php.ini file: display_errors = Off
• log_error setting specifies whether error messages should or should
not be sent to the server error log log_errors = On

12. PHP Error and Exception handling
• Two mechanisms for handling runtime errors:
■ procedural error handling
■ Object-Oriented exception handling
• procedural approach to error handling, the programmer needs to
explicitly test for error conditions after performing a task that might
generate an error.
If(condition){ some code here } else { }
• When a runtime error occurs, PHP throws an exception. This
exception can be caught and handled either by the function, class, or
page that generated the exception or by the code that called the
function or class using
try{ condition} catch(Exception e) {}

13. PHP Error and Exception handling
• Custom error and exception handlers
• It should provide the developer with detailed information
about the state of the application when the exception
occurred, information about the exception, and when it
happened.
• It should hide any of those details from the regular end user,
and user with a generic message such as “Sorry but there was
a problem,” or “Sorry but the system is down for
maintenance.”
Function myException($Exception)
{ Our own exception message / Code here }

14. Source Reference: Randy Connolly, Ricardo Hoar, Fundamentals of Web Development, Pearson
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