What's New in PHP 7

The following are some of the new features PHP 7

1 - Scalar type declarations : if you use the declare(strict_types=1); then the parameter would be strict, i.e folat means float only if you pass anything else it will through the error,

declare(strict_types=1);
function returnsum(float $a, float $b)
 {
return $a + $b;
}
returnsum(3.1, 2.1);
// output float(5.2)
returnsum(3, "2 days");
// Fatal error

2 - Return type declaration : same as scaler type declaration, we can use the return with in a function with strictly.

declare(strict_types=1);
function add($a, $b): int {
return $a + $b;
}
var_dump(add(1, 2));
var_dump(add(1, 2.5));
// output will be
// int(3)
// Fatal error

3 - Null Coalescing Operator : if the value is exists and not null, then it returns the first operand, otherwise it returns the second operand.
$username = $_GET['username'] ?? 'not define';

// Fetches the value of $_GET['username'] and returns 'not define'
// if it does not exist.
$username = $_GET['username'] ?? 'not define';
// This is same as to:
$username = isset($_GET['username']) ? $_GET['username'] : 'not define';
// Coalescing can be chained: this will return the first
// defined value out of $_GET['username'], $_POST['username'], and
// 'not define'.
$username = $_GET['username'] ?? $_POST['username'] ?? 'not define';

4 - Spaceship Operator : The Spaceship operator is represented like this <=>. It is used to compare two expressions and return -1, 0, 1 when one variable is less than, equal to, or greater than, as compared to the other variable.

// Integers
echo 1 <=> 1; // 0
echo 1 <=> 2; // -1
echo 2 <=> 1; // 1

5 - What are constant arrays that use define()?
In PHP 7, you can also define the array as a constant by using define.
define('NAME', array('Chandar','Ram','Gugu'));
echo NAME[1]; // outputs "Chandar"

6 - Error Handling : In PHP 7, an exception will be thrown when a fatal and recoverable error occurs, rather than just stopping the script. Fatal errors still exist for certain conditions, such as running out of memory, and still behave as before by immediately stopping the script. An uncaught exception will also continue to be a fatal error in PHP 7. This means if an exception thrown from an error that was fatal in PHP 5 goes uncaught, it will still be a fatal error in PHP 7.
I want to point out that other types of errors such as warnings and notices remain unchanged in PHP 7. Only fatal and recoverable errors throw exceptions.

7 - Easy User-land CSPRNG(Cryptographically Secure PseudoRandom Number Generator )

There are random number generators in PHP, rand() for instance, but none of the options in version 5 are very secure. In PHP 7, they put together a system interface to the operating system’s random number generator. Because we can now use the operating system’s random number generator, if that gets hacked we have bigger problems. It probably means your entire system is compromised and there is a flaw in the operating system itself.

You now have 2 new functions to use: random_int and random_bytes. 

$bytes = random_bytes(5); // length in bytes 
// output similar to: string(10) "385e33f741"
These are bytes not integers. If you are looking to return a random number, or integer, you should use the random_int function.

random_int(1,20);
Would return a random number between 1 and 20, including the possibility of 1 and 20.

Pass by value and Pass by reference in php:

Pass by Value only change the value temporarly while reference by change the value in memory(at the memeory address).

By reference variable, the value permanently change the value while in pass by value temporary change the value.

 function foo(&$var)  
 {  
   $var++;  
 }  
 $a=5;  
 foo($a);  
 echo $a;  

With reference variable the putput would be the 6 While without reference the output would be 5.