Analyze the difference between php7 and PHP5 in detail

#There are two main modes: mandatory mode and strict mode
declare(strict_types=1)
#1 indicates strict type verification mode, which is used for function calls and return statements; 0 indicates weak type verification mode.

$site = isset($_GET['site']) ? $_GET['site'] : 'wo';
#Abbreviated as
$site = $_GET['site'] ??'wo';

//Integer comparison
print( 1 <=> 1);print(PHP_EOL);
print( 1 <=> 2);print(PHP_EOL);
print( 2 <=> 1);print(PHP_EOL);
print(PHP_EOL); //  PHP_ EOL is a newline character
//Results:
0
-1
1

//Use the define function to define an array
define('sites', [
   'Google',
   'Jser',
   'Taobao'
]);

print(sites[1]);

interface Logger { 
   public function log(string $msg); 
} 

class Application { 
   private $logger; 

   public function getLogger(): Logger { 
      return $this->logger; 
   } 

   public function setLogger(Logger $logger) { 
      $this->logger = $logger; 
   }   
} 

$app = new Application; 
//Create an anonymous class using new class 
$app->setLogger(new class implements Logger { 
   public function log(string $msg) { 
      print($msg); 
   } 
}); 

$app - > getlogger() - > log ("my first log");

<?php 
class A { 
    private $x = 1; 
} 

//Closure function code defined in PHP before version 7 
$getXCB = function() { 
    return $this->x; 
}; 

//The closure function is bound to class A 
$getX = $getXCB->bindTo(new A, 'A');  

echo $getX(); 
print(PHP_EOL); 

//PHP 7 + code 
$getX = function() { 
    return $this->x; 
}; 
echo $getX->call(new A); 
?>

#Class abbreviations under the same namespace can be imported
use some\namespace\{ClassA, ClassB, ClassC as C};

//1. session_ Start() can define an array
<?php
session_start([
   'cache_limiter' => 'private',
   'read_and_close' => true,
]);
?>
//2. Introduced a new PHP Ini setting (session. Lazy_write), which is set to true by default, means that session data is written only when it changes.