Once called annotations, ATTRIBUTES carry metadata for classes, properties or methods.

ATTRIBUTES are usually introduced in docblocks with an @

With PHP 8.0, they are flagged with a different syntax even if their operating mode remains the same.

To access the Attributes info, a few changes have been added to the Reflection API.

For example, the function `getAttributes( )` retrieves the names and data of the Attributes associated with an object, a method, etc.

SWITCH statements have been criticized for their tricky structure and their lack of flexibility.

MATCH structure is lighter and flexible. It is now possible to suggest multiple values and separate them with a comma.

MATCH doesn't require a default option.

However if the input that we seek to compare has no "match" (hehe) and the MATCH statement has no default option, it triggers an error.

SWITCH allows large comparisons...

Unnecessary directive "strict-type" has been removed to avoid confusion

Switch operates a large comparison :

 '2'  == 2 is true.

... whereas MATCH operates strict ones.

Match operates a strict comparison :

'2' === 2 is false

An UnhandledMatchError exception is thrown

`STR_CONTAINS( )` checks if a string contains a given substring.

The comparison is case-sensitive.

`STR_STARTS_WITH( )` checks if a string starts with a given substring.

The comparison is case-sensitive.

`STR_ENDS_WITH( )` checks if a string ends with a given substring.

The comparison is case-sensitive.

Dividing any int or float by zero used to be forbidden. It'd throw a `DivisionByZeroError`, whether we use `/`, `%`, `intdiv( )` or ` fmod( )`.

The new `FDIV( )` function works as the division operator.

But its advantage is that it allows the division of any int or float by zero. It doesn't throw an error. It returns `INF`, `- INF` or `NAN` instead.

These output are more informative and useful for debugging.

In this example, the dividend is positive, so the output is INF

When a positive number is divided by zero, the output is `INF`.

In this example, the dividend is negative, so the output is -INF

When a negative number is divided by zero, the output is `-INF`.

In this example, the dividend is zero, so the output is NAN.

When the dividend and the divisor are zeroes, the output is `NAN`.

RESOURCE is a PHP special type (like NULL). It designates data that are external to PHP.

There is a list of internal functions which create, use, handle or destroy resources.

For instance, the now deprecated `mysql_connect( )` function used to create a mysql link resource and open a connection to a MySQL database, whereas `mysql_close( )` (also deprecated) used to destroy the formerly created mysql link.

For more on this, see  : https://www.php.net/manual/fr/resource.php

The `get_resource_type` function, which has first been introduced with PHP 4, allows to determine a resource type.

We've also been able to retrieve the id of a given resource by casting it to an integer.

After creating a temporary file resource, we cast it to an integer to force the retrieval of its id (here, it's 4). It is not safe.

PHP 8 introduces the `get_resource_id` function, which makes the retrieval of a resource id easier.

There are several PCRE functions. They use regex and find occurrences within strings. They start with prefix`preg_`, like `preg_match( )`.

PCRE means Perl Compatible Regular Expression. It designates what we usually call regex, or regular expressions.

While running theses functions, errors can be spotted in the structure of regex. A list of constants and their respective codes are designed to inform on the origin of theses errors.

PHP 8 introduces `preg_last_error_message( )`, which retrieves the error message (stored in a constant such as `PREG_BACKTRACK_LIMIT`).

We can read the error code thanks to `preg_last_error( )`.

For more on this, see  :

https://www.php.net/manual/fr/pcre.constants.php

DateTime and DateTimeImmutable objects are instances of DateTimeInterface. DateTime objects are mutable, whereas DateTimeImmutable objects return a new object when a modifier is applied on them.

We can create a DateTime object from a DateTimeImmutable object.

But creating a DateTimeImmutable object from a DateTime object is complicated.

See RFC : https://wiki.php.net/rfc/always_enable_json

In previous versions of PHP, the `ext-json` extension was optional.

But as the community use JSON format a lot, it's appeared natural to include the extension in PHP.

Starting with PHP 8, the `ext-json` extension is always available. We can disable it if needed.