Understanding and comparing new features of php7

1. null coalescing operator (??)

?? Syntax: If the variable exists And the value is not NULL, it will return its own value, otherwise it will return its second operand.

//php7以前  if判断 
if(empty($_GET['param'])) { 
     $param = 1; 
}else{ 
    $param = $_GET['param']; 
} 
  
//php7以前  三元运算符 
$param = empty($_GET['param']) ? 1 : $_GET['param'];

//PHP7  null合并运算符
 
 $param = $_GET['param'] ?? 1;//1

2. define() defines a constant array

 //php7以前 
 define("CONTENT", "hello world"); 
  echo CONTENT;//hello world 
  
 //PHP7 
 define('ANIMALS', [ 
    'dog', 
     'cat', 
    'bird'
]);
 echo ANIMALS[2];//bird

 //PHP7 类外也可使用const来定义常量
 const CONSTANT = 'Hello World'; 
 echo CONSTANT;//Hello World

3. Combined comparison operators ()

The combined comparison operator is used to compare two expressions. It returns -1, 0 or 1 respectively when $a is less than, equal to or greater than $b. The principle of comparison is to follow the general comparison rules of PHP.

 /整数 
echo 1  1; // 0 
echo 1  2; // -1 
echo 2  1; // 1 
 
 //浮点数 
echo 1.5  1.5; // 0 
echo 1.5  2.5; // -1 
echo 2.5  1.5; // 1
  
  //字符串
echo "a"  "a"; // 0
echo "a"  "b"; // -1
echo "b"  "a"; // 1

4. Variable type declaration

Two modes: forced (default) and strict mode. The following type parameters can be used: string, int, float, bool

  //... 操作符: 表示这是一个可变参数. php5.6及以上的版本可使用: 函数定义的时候变量前使用. 
  function intSum(int ...$ints){ 
     return array_sum($ints); 
  } 
 var_dump(intSum(2,'3.5'));//5 
   
  //严格模式 
  //模式声明：declare(strict_types=1);  默认情况值为0，值为1代表为严格校验的模式  
  declare(strict_types=1);
  function add(int $a,int $b){
      return $a+$b;
  }
  var_dump(add(2,'3.5')); //Fatal error: Uncaught TypeError: Argument 2 passed to add() must be of the type integer

5. Return value type declaration

Add support for return type declaration. Similar to parameter type declaration. (For usage, add: type name after the function definition)

 //有效的返回类型
declare(strict_types = 1);
 function getInt(int $value): int {
   return $value;
 }
 print(getInt(6));//6

//无效返回类型
declare(strict_types = 1);
 function getNoInt(int $value): int {
   return $value+'2.5';
 }
 print(getNoInt(6));//Fatal error: Uncaught TypeError: Return value of getNoInt() must be of the type integer

6. Anonymous class

Allows new class {} to create a Anonymous object.

  <?php  
  //php7以前 接口实现 
  interface User{ 
      public function getDiscount(); 
  } 
  class VipUser implements User{ 
      //折扣系数 
      private $discount = 0.6; 
      public function getDiscount() {
          return $this->discount;
      }
  }
  class Goods{
      private $price = 200;
      private $objectVipUser;
      //User接口VipUser类实现
      public function getUserData($User){
          $this->objectVipUser = $User;
          $discount = $this->objectVipUser->getDiscount();
          echo "商品价格:".$this->price*$discount;
      }
  }
  $display = new Goods();
  //常规实例化接口实现对象
  $display ->getUserData(new VipUser);//商品价格:120

  <?php  
  //php7 创建一个匿名的对象 
  interface User{ 
      public function getDiscount(); 
  } 
  class Goods{ 
      private $price = 200; 
      private $objectVipUser; 
      public function getUserData($User){
          $this->objectVipUser = $User;
          $discount = $this->objectVipUser->getDiscount();
          echo "商品价格:".$this->price*$discount;
      }
  }
  $display = new Goods();
  //new匿名对象实现user接口
  $display ->getUserData(new class implements User{
      private $discount = 0.6;
      public function getDiscount() {
          return $this->discount;
      }
  });//商品价格:120

7. Closure::call()

The Closure::call() method was added as a short way to temporarily bind an object scope to a closure and call it. Its performance is much faster compared to PHP5's bindTo. .

  <?php  
  //php7以前 
  class A { 
      private  $attribute = &#39;hello world&#39;; 
  } 
   
  $getClosure = function(){ 
      return $this->attribute; 
  };
  
  $getAttribute = $getClosure->bindTo(new A, 'A');//中间层闭包
  echo $getAttribute();//hello world

  <?php  
  //PHP7 
  class A { 
      private  $attribute = &#39;hello world&#39;; 
  } 
   
  $getClosure = function(){ 
      return $this->attribute; 
  };
  
  echo $getClosure->call(new A);//hello world

8. unserialize()

unserialize() function: The filtering feature can prevent code injection of illegal data and provide safer deserialized data

  <?php  
  class A{  
     public $name = &#39;admin_a&#39;;    
  } 
  class B{ 
     public $name = &#39;admin_b&#39;; 
  } 
  $objA = new A(); 
 $objB = new B(); 
 $serializedObjA = serialize($objA); 
 $serializedObjB = serialize($objB); 
 //默认行为是接收所有类; 第二个参数可以忽略
 $dataA = unserialize($serializedObjA , ["allowed_classes" => true]); 
 var_dump($dataA);//object(A)#3 (1) { ["name"]=> string(7) "admin_a" }
//如果allowed_classes设置为false,unserialize会将所有对象转换为__PHP_Incomplete_Class对象 
 $dataA = unserialize($serializedObjA , ["allowed_classes" => false]); 
 var_dump($dataA);//object(__PHP_Incomplete_Class)#4 (2) { ["__PHP_Incomplete_Class_Name"]=> string(1) "A" ["name"]=> string(7) "admin_a" }
//转换所有对象到 __PHP_Incomplete_Class对象，除了对象"B"
 $dataB = unserialize($serializedObjB , ["allowed_classes" => ["B"]]); 
var_dump($dataB);//object(B)#3 (1) { ["name"]=> string(7) "admin_b" }

9. IntlChar

IntlChar: Provides access to some utility methods that can be used to access Unicode character information . Note: Intl extension must be installed to use!

var_dump(IntlChar::CODEPOINT_MAX);//int(1114111) 
echo '<br>';
var_dump(IntlChar::charName('+'));//string(9) "PLUS SIGN" 
echo '<br>';
var_dump(IntlChar::ispunct('?'));//bool(true)

10. CSPRNG

The CSPRNG function provides a simple mechanism to generate cryptographic random numbers.

random_bytes() - Cryptographically protected pseudo-random string.

random_int() - A cryptographically protected pseudo-random integer.

$bytes = random_bytes(8); 
echo(bin2hex($bytes));//随机2073a110a2e3c497
echo '<br>';
echo(random_int(1, 999));//随机786
echo '<br>';
print(random_int(-999, -1));//随机-357

11. use statement

You can use a single use statement to import classes, functions and constants from the same namespace instead of using multiple use statements.

 //PHP7之前 
use some\namespace\ClassA; 
use some\namespace\ClassB; 
use some\namespace\ClassC as C; 
use function some\namespace\fn_a;
use function some\namespace\fn_b; 
use function some\namespace\fn_c; 
use const some\namespace\ConstA; 
use const some\namespace\ConstB;
use const some\namespace\ConstC;
// PHP7之后
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};

12. intp

Newly added intp() function, receiving two parameters, the return value is the value of the first parameter divided by the second parameter and rounded.

##

echo intp(8,4);//2
echo intp(10,4);//2
echo intp(5,10);//0

13. PHP7 error handling

PHP7 改变了大多数错误的报告方式.不同于PHP5的传统错误报告机制,现在大多数错误被作为Error异常抛出.

这种Error异常可以像普通异常一样被try / catch块所捕获. 如果没有匹配的try / catch块,则调用异常处理函数（由 set_exception_handler() 注册）进行处理.
如果尚未注册异常处理函数,则按照传统方式处理：被报告为一个致命错误（Fatal Error）.

Error类并不是从Exception类扩展出来的,所以用catch (Exception $e) { ... } 这样的代码是捕获不到Error的.你可以用 catch (Error $e) { ... } 这样的代码，
或者通过注册异常处理函数（ set_exception_handler()）来捕获Error.

  <?php  
  //php7以前 自定义异常处理 
  class getException extends Exception{ 
      public function errorMsg(){ 
          return &#39;错误的信息&#39;.$this->getMessage().'<br>错误的代码'.$this->getCode(); 
      } 
  } 
   
  try {
      $num =10;
      if($num > 1) {
          throw new getException($num,404);
      }
  } catch (getException $e) {
      echo $e->errorMsg();
    }

 <?php   
 //php7 异常处理
 try {
     test();
 }catch(Error $e) {
     echo $e->getMessage();//Call to undefined function test()
      }

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