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PHP Core

Typed properties

Class properties now support type declarations.

class User {
int $id;
string $name;
The above example will enforce that $user->id can only be assigned int values and $user->name can only be assigned string values.

Arrow functions

Arrow functions provide a shorthand syntax for defining functions with implicit by-value scope binding.

= 10;
$nums = array_map(fn($n) => $n * $factor, [1, 2, 3, 4]);
// $nums = array(10, 20, 30, 40);

Limited return type covariance and argument type contravariance

The following code will now work:

class A {}
B extends A {}

Producer {
public function
method(): A {}
ChildProducer extends Producer {
public function
method(): B {}
Full variance support is only available if autoloading is used. Inside a single file only non-cyclic type references are possible, because all classes need to be available before they are referenced.

Null coalescing assignment operator

['key'] ??= computeDefault();
// is roughly equivalent to
if (!isset($array['key'])) {
$array['key'] = computeDefault();

Unpacking inside arrays

= ['apple', 'pear'];
$fruits = ['banana', 'orange', ...$parts, 'watermelon'];
// ['banana', 'orange', 'apple', 'pear', 'watermelon'];

Numeric literal separator

Numeric literals can contain underscores between digits.

; // float
299_792_458; // decimal
0xCAFE_F00D; // hexadecimal
0b0101_1111; // binary

Weak references

Weak references allow the programmer to retain a reference to an object that does not prevent the object from being destroyed.

Allow exceptions from __toString()

Throwing exceptions from __toString() is now permitted. Previously this resulted in a fatal error. Existing recoverable fatal errors in string conversions have been converted to Error exceptions.


CURLFile now supports stream wrappers in addition to plain file names, if the extension has been built against libcurl >= 7.56.0.


The FILTER_VALIDATE_FLOAT filter now supports the min_range and max_range options, with the same semantics as FILTER_VALIDATE_INT.


FFI is a new extension, which provides a simple way to call native functions, access native variables, and create/access data structures defined in C libraries.


Added the IMG_FILTER_SCATTER image filter to apply a scatter filter to images.


Added crc32c hash using Castagnoli's polynomial. This CRC32 variant is used by storage systems, such as iSCSI, SCTP, Btrfs and ext4.

Multibyte String

Added the mb_str_split() function, which provides the same functionality as str_split(), but operating on code points rather than bytes.


Support for preloading code has been added.

Regular Expressions (Perl-Compatible)

The preg_replace_callback() and preg_replace_callback_array() functions now accept an additional flags argument, with support for the PREG_OFFSET_CAPTURE and PREG_UNMATCHED_AS_NULL flags. This influences the format of the matches array passed to to the callback function.


The username and password can now be specified as part of the PDO DSN for the mysql, mssql, sybase, dblib, firebird and oci drivers. Previously this was only supported by the pgsql driver. If a username/password is specified both in the constructor and the DSN, the constructor takes precedence.

It is now possible to escape question marks in SQL queries to avoid them being interpreted as parameter placeholders. Writing ?? allows sending a single question mark to the database and e.g. use the PostgreSQL JSON key exists (?) operator.


PDOStatement::getColumnMeta() is now available.


PDOStatement::getAttribute(PDO::SQLITE_ATTR_READONLY_STATEMENT) allows checking whether the statement is read-only, i.e. if it doesn't modify the database.

PDO::setAttribute(PDO::SQLITE_ATTR_EXTENDED_RESULT_CODES, true) enables the use of SQLite3 extended result codes in PDO::errorInfo() and PDOStatement::errorInfo().


Added SQLite3::lastExtendedErrorCode() to fetch the last extended result code.

Added SQLite3::enableExtendedResultCodes($enable = true), which will make SQLite3::lastErrorCode() return extended result codes.


strip_tags() with array of tag names

strip_tags() now also accepts an array of allowed tags: instead of strip_tags($str, '<a><p>') you can now write strip_tags($str, ['a', 'p']).

Custom object serialization

A new mechanism for custom object serialization has been added, which uses two new magic methods: __serialize and __unserialize.

// Returns array containing all the necessary state of the object.
public function __serialize(): array;

// Restores the object state from the given data array.
public function __unserialize(array $data): void;
The new serialization mechanism supersedes the Serializable interface, which will be deprecated in the future.

Array merge functions without arguments

array_merge() and array_merge_recursive() may now be called without any arguments, in which case they will return an empty array. This is useful in conjunction with the spread operator, e.g. array_merge(...$arrays).

proc_open() function

proc_open() now accepts an array instead of a string for the command. In this case the process will be opened directly (without going through a shell) and PHP will take care of any necessary argument escaping.

(['php', '-r', 'echo "Hello World\n";'], $descriptors, $pipes);

proc_open() now supports redirect and null descriptors.

// Like 2>&1 on the shell
proc_open($cmd, [1 => ['pipe', 'w'], 2 => ['redirect', 1]], $pipes);
// Like 2>/dev/null or 2>nul on the shell
proc_open($cmd, [1 => ['pipe', 'w'], 2 => ['null']], $pipes);

argon2i(d) without libargon

password_hash() now has the argon2i and argon2id implementations from the sodium extension when PHP is built without libargon.

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User Contributed Notes 2 notes

4 years ago
It should be noted that typed properties internally are never initialized to a default null. Unless of course you initialize them to null yourself. That's why you will always going to encounter this error if you try to access them before initialization.

**Typed property foo::$bar must not be accessed before initialization**

class User
string $name; // Typed property (Uninitialized)
public ?string $age = null; // Typed property (Initialized)

$user = new User;
var_dump(is_null($user->id)); // bool(true)
var_dump(is_null($user->name)); // PHP Fatal error: Typed property User::$name must not be accessed before initialization
var_dump(is_null($user->age));// bool(true)

Another thing worth noting is that it's not possible to initialize a property of type object to anything other than null. Since the evaluation of properties happens at compile-time and object instantiation happens at runtime. One last thing, callable type is not supported due to its context-dependent behavior.
4 years ago

// How to get property type? For example for testing:

class Foo
int $num;
bool $isPositive;

$reflection = new \ReflectionClass(Foo::class);
$classProperties = $reflection->getProperties(\ReflectionProperty::IS_PRIVATE);
foreach (
$classProperties as $classProperty) {
var_dump((string) $classProperty->getType());

* Result:
* "int"
* "bool"
* ""
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