PHP 7 new features

Following are PHP 7 new features

Scalar type declarations: In this we can declare what type of argument will be accepted by functions.

function sumOfInts(int ...$all_ints){ /** It will accept only integers **/
    return array_sum($all_ints);
}
echo sumOfInts(2, 3); //5
echo sumOfInts(2, '3', '5'); //10
echo sumOfInts(2, '3', 'string'); //Error: Uncaught TypeError: Argument 3 passed to sumOfInts() must be of the type integer, string given

Return type declarations : In this we can declare what what will be the datatype from functions.
```
function sumOfInts(int ...$all_ints):int
{
    return array_sum($all_ints);
}
echo sumOfInts(2, 3); //5
echo sumOfInts(2, '3', '5'); //10
```
Here if function "sumOfInts" return an string OR Array, it will give error.

Null coalescing operator (??) have been added.

$userId = $_GET['user_id'] ?? '0';

is equivalent to

$userId = isset($_GET['user_id']) ? $_GET['user_id'] : '0';

Spaceship operator :The spaceship operator is used for comparing two expressions. It returns -1, 0 or 1
```
echo 1 <=> 1; // 0
echo 1 <=> 2; // -1
echo 2 <=> 1; // 1
```

define() updates: Now you can add array.

define('CLIENTS', [
    'client 1',
    'client 2',
    'client 3'
]);

echo CLIENTS[1];//client 2

Unicode codepoint escape syntax
```
echo "\u{aa}";
echo "\u{9999}";
```

Closure::call Temporarily binding an object scope to a closure and invoking it.

class A {private $x = 1;}
$getX = function() {return $this->x;};
echo $getX->call(new A);

unserialize updates: Provide better security when unserializing objects on untrusted data and prevents possible code injections by enabling the developer to whitelist classes that can be unserialized.
```
$data = unserialize($searilizedData, ["allowed_classes" => ["MyClass", "MyClass2"]]);
```
list() function updates: Now list() can unpack the object also. Earlier it unpack int, float, string and array only.
session_start() function updates:
Now you can pass array-options in this function. For Example:
```
session_start([
    'cache_limiter' => 'private',
    'read_and_close' => true,
]);
```
intdiv() new function It performs an integer division of its operands and returns it. For Example:
```
echo intdiv(100, 3); //33
```
use updations Classes, functions and constants being imported from the same namespace can now be grouped together in a single use statement Below both are Same.
```
use some\namespace\ClassA;
use some\namespace\ClassB;
use some\namespace\ClassC as C;
```
OR
```
use some\namespace\{ClassA, ClassB, ClassC as C};
```

CSPRNG Functions i.e. random_bytes() and random_int()

$bytes = random_bytes(5);
var_dump(bin2hex($bytes)); //string(10) "385e33f741"
var_dump(random_int(1, 100));//1-100

Generator delegation: Generators can now delegate to another generator using yield, Traversable object/array automatically.

function func1()
{
    yield 1;
    yield 2;
    yield from func2();
}

function func2()
{
    yield 3;
    yield 4;
}

foreach (func1() as $val)
{
    echo $val, PHP_EOL;
}
/** Output 
1
2
3
4
Output **/