New features
Constant expressions
It is now possible to provide a scalar expression involving numeric and string literals and/or constants in contexts where PHP previously expected a static value, such as constant and property declarations and default function arguments.
<?php
const ONE = 1;
const TWO = ONE * 2;
class C {
const THREE = TWO + 1;
const ONE_THIRD = ONE / self::THREE;
const SENTENCE = 'The value of THREE is '.self::THREE;
public function f($a = ONE + self::THREE) {
return $a;
}
}
echo (new C)->f()."\n";
echo C::SENTENCE;
?>
The above example will output:
4 The value of THREE is 3
It is also now possible to define a constant array using the const keyword:
<?php
const ARR = ['a', 'b'];
echo ARR[0];
?>
The above example will output:
a
Variadic functions via ...
Variadic functions can now be implemented using the ... operator, instead of relying on func_get_args().
<?php
function f($req, $opt = null, ...$params) {
// $params is an array containing the remaining arguments.
printf('$req: %d; $opt: %d; number of params: %d'."\n",
$req, $opt, count($params));
}
f(1);
f(1, 2);
f(1, 2, 3);
f(1, 2, 3, 4);
f(1, 2, 3, 4, 5);
?>
The above example will output:
$req: 1; $opt: 0; number of params: 0 $req: 1; $opt: 2; number of params: 0 $req: 1; $opt: 2; number of params: 1 $req: 1; $opt: 2; number of params: 2 $req: 1; $opt: 2; number of params: 3
Argument unpacking via ...
Arrays and Traversable objects can be unpacked into argument lists when calling functions by using the ... operator. This is also known as the splat operator in other languages, including Ruby.
<?php
function add($a, $b, $c) {
return $a + $b + $c;
}
$operators = [2, 3];
echo add(1, ...$operators);
?>
The above example will output:
6
Exponentiation via **
A right associative ** operator has been added to support exponentiation, along with a **= shorthand assignment operator.
<?php
printf("2 ** 3 == %d\n", 2 ** 3);
printf("2 ** 3 ** 2 == %d\n", 2 ** 3 ** 2);
$a = 2;
$a **= 3;
printf("a == %d\n", $a);
?>
The above example will output:
2 ** 3 == 8 2 ** 3 ** 2 == 512 a == 8
use function and use const
The use operator has been extended to support importing functions and constants in addition to classes. This is achieved via the use function and use const constructs, respectively.
<?php
namespace Name\Space {
const FOO = 42;
function f() { echo __FUNCTION__."\n"; }
}
namespace {
use const Name\Space\FOO;
use function Name\Space\f;
echo FOO."\n";
f();
}
?>
The above example will output:
42 Name\Space\f
phpdbg
PHP now includes an interactive debugger called phpdbg implemented as a SAPI module. For more information, please visit the phpdbg documentation.
Default character encoding
default_charset is now used as the default character set for the htmlentities(), html_entity_decode() and htmlspecialchars() functions. Note that if the (now deprecated) iconv and mbstring encoding settings are set, they will take precedence over default_charset for iconv and mbstring functions, respectively.
The default value for this setting is UTF-8.
php://input is reusable
php://input may now be reopened and read as many times as required. This work has also resulted in a major reduction in the amount of memory required to deal with POST data.
GMP supports operator overloading
GMP objects now support operator overloading and casting to scalar types. This allows for more expressive code using GMP:
<?php
$a = gmp_init(42);
$b = gmp_init(17);
if (version_compare(PHP_VERSION, '5.6', '<')) {
echo gmp_intval(gmp_add($a, $b)), PHP_EOL;
echo gmp_intval(gmp_add($a, 17)), PHP_EOL;
echo gmp_intval(gmp_add(42, $b)), PHP_EOL;
} else {
echo $a + $b, PHP_EOL;
echo $a + 17, PHP_EOL;
echo 42 + $b, PHP_EOL;
}
?>
The above example will output:
59 59 59
hash_equals() for timing attack safe string comparison
The hash_equals() function has been added to compare two strings in constant time. This should be used to mitigate timing attacks; for instance, when testing crypt() password hashes (assuming that you are unable to use password_hash() and password_verify(), which aren't susceptible to timing attacks).
<?php
$expected = crypt('12345', '$2a$07$usesomesillystringforsalt$');
$correct = crypt('12345', '$2a$07$usesomesillystringforsalt$');
$incorrect = crypt('1234', '$2a$07$usesomesillystringforsalt$');
var_dump(hash_equals($expected, $correct));
var_dump(hash_equals($expected, $incorrect));
?>
The above example will output:
bool(true) bool(false)
__debugInfo()
The __debugInfo() magic method has been added to allow objects to change the properties and values that are shown when the object is output using var_dump().
<?php
class C {
private $prop;
public function __construct($val) {
$this->prop = $val;
}
public function __debugInfo() {
return [
'propSquared' => $this->prop ** 2,
];
}
}
var_dump(new C(42));
?>
The above example will output:
object(C)#1 (1) {
["propSquared"]=>
int(1764)
}
gost-crypto hash algorithm
The gost-crypto hash algorithm has been added. This implements the GOST hash function using the CryptoPro S-box tables as specified by » RFC 4357, section 11.2.
SSL/TLS improvements
A wide range of improvements have been made to the SSL/TLS support in PHP 5.6. These include enabling peer verification by default, supporting certificate fingerprint matching, mitigating against TLS renegotiation attacks, and many new SSL context options to allow more fine grained control over protocol and verification settings when using encrypted streams.
These changes are described in more detail in the OpenSSL changes in PHP 5.6.x section of this migration guide.
pgsql async support
The pgsql extension now supports
asynchronous connections and queries, thereby enabling non-blocking
behaviour when interacting with PostgreSQL databases. Asynchronous
connections may be established via the
PGSQL_CONNECT_ASYNC constant, and the new
pg_connect_poll(), pg_socket(),
pg_consume_input() and pg_flush()
functions may be used to handle asynchronous connections and queries.
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Document created the 30/01/2003, last modified the 26/10/2018
Source of the printed document:https://www.gaudry.be/en/php-rf-migration56.new-features.php.html
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