PHP 7 New Features

Question: What are main features of PHP 7?

1. Lower Memory Consumption
2. Improved performance as now using Zend Engine 3.0
3. Consistent 64-bit support
4. Scalar type declarations
5. Return type declarations
6. define() updates: Now you can add array.
7. unserialize updates: Provide better security when unserializing objects on untrusted data
8. Anonymous classes can be created
9. Null coalescing operator (??) have been added

   Namespaces declaration like use some\namespace\{ClassA, ClassB, ClassC as C};

10. Many fatal errors converted to Exceptions
11. Secure random number generator
12. session_start will accept an array.
13. Spaceship operator
14. list() function updates

Question: What is null coalescing operator?
null coalescing operator (??) has been introduced in PHP7.

$username = $_GET['username'] ?? $_POST['username'] ?? 'not passed';
print($username);

Question: What are Scalar type declarations?
Scalar type declarations has two type of options.

1. coercive - coercive is default mode and need not to be specified.
2. strict - strict mode has to explicitly hinted.

Question: What is Namespaces?
Namespaces are a way of encapsulating items. we can use two more different classes into one Namespaces.


Question: What is purpose of Namespaces?
1) To fixed the name collisions between your code and internal PHP classes/functions/constants or third-party classes/functions/constants.
2) Ability to shorten for Extra_Long_Names, improving readability of source code.



Question: Explain about Namespaces in PHP7?

1. Namespace must be the first statement in the PHP Script.
2. We can define Sub-Namespace also
3. Defining multiple namespaces in same file with/without using bracketed syntax (Multiple declaration is not Recommended)
4. We can access the Global method of namespaces using \

   namespace A\B\C;
           function strlen($string){
               return \strlen($string).'--arun';
           }
       echo strlen('imarun');

5. we can use __NAMESPACE__ for getting the current namespace name
6. We can use Alias for namespace as below

   use mynamespace\car as mycar;

7. import multiple namespaces in single line

   use some\namespace\{ClassA, ClassB, ClassC as C};
           use function some\namespace\{fn_a, fn_b, fn_c};
           use const some\namespace\{ConstA, ConstB, ConstC};  

8. Using namespaces: fallback to global function/constant
   a) An unqualified class name resolve to current namespace
   b) An unqualified function name resolve to current namespace
   c) An unqualified constant name resolve to Global namespace
   

Question: What is Class Constants?
Class Constants: You can define constant as string OR expression. but you can not define as variable, or function.


Question: When autoloading classes loads automatic?
a) Autoload when create object.
b) Autoload when include an another (using extends)
c) Autoload when include an interface (using implements )
d) we Can add exception in spl_autoload_register


Question: What is Visibility?
Class methods must be declare as public, protected or private.
You can also declare with var which means public


Question: What are Static Keyword?
Declaring class property or methods as static makes them accessible without needing an instantiation of the class.
$this is not available inside the function.

PHP namespace example - Tutorial

Question: What is namespace in PHP?
namespace is reserve keywords which is used to encapsulating the class, method, data member variables and static methods.


Question: Benefits of namespace in PHP?

1. Encapsulate the data which fixed collisions between code you create, and internal PHP classes/functions/constants.
2. Ability to alias which improved the readability of source code.

Question: Which PHP Version support namespaces?

PHP5.3

Question: How namespaces are defined?
namespaces are defined with keyword namespace
For Example:

namespace math

Question: Example - Simple class without namespace (OR Global namespace)?
File: /myproject/simple-file.php

class mathSimple {

    function add($a, $b) {
        return $a + $b;
    }

}

File: /myproject/run-example.php

include "simple-file.php";

$obj1 = new mathSimple(); //calling for Global Namespace
echo $obj1->add(10,20);//30

When we execute run-example.php file, it will return 30


Question: Example - Simple class with namespace?
File: /myproject/namespace-file.php

namespace math;

class mathSimple {

    function add() {        
        return array_sum(func_get_args()) ;
    }

}

File: /myproject/run-example.php

namespace math;
include "simple-file.php";
include "namespace-file.php";


$obj1 = new \mathSimple(); //calling for Global Namespace
echo $obj1->add(10,20,30);

echo "\n";
$obj2 = new mathSimple(); //calling for namespace math
echo $obj2->add(10,20,30);

Question: How to import namespaces?

use Zend\View\Model\ViewModel;

Question: How to use alias namespaces for import namespace?

use Zend\View\Model\ViewModel as ZendViewModel;

Question: Can we override the php in-built using namespace?
Yes, We can do. File: /myproject/namespace-file2.php

namespace math;

class mathSimple {

    function add() {        
        return array_sum(func_get_args()) ;
    }

}
function strlen($string){
    return 'in built functi';
}

File: /myproject/run-example2.php

namespace math;
include "namespace-file2.php";

echo strlen('string'); //calling namespace function
echo \strlen('strlen'); //calling inbuilt function

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