Understand and compare new features of php7

# Recommended (free): 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.

 1 //php7以前  
 if判断 
 2 if(empty($_GET['param'])) { 
 3       $param = 1; 
 4 }else{ 
 5     $param = $_GET['param']; 
 6 } 7  
 8 //php7以前  三元运算符 
 9 $param = empty($_GET['param']) ? 1 : $_GET['param'];10 
 11 //PHP7  null合并运算符12 $param = $_GET['param'] ?? 1;//1

2. define() defines a constant array

 1 //php7以前 
 2 define("CONTENT", "hello world"); 
 3 echo CONTENT;//hello world 4  
 5 //PHP7 6 define('ANIMALS', [ 
 7     'dog', 
 8     'cat', 
 9     'bird'
 10 ]);
 11 echo ANIMALS[2];//bird12 
 13 //PHP7 类外也可使用const来定义常量
 14 const CONSTANT = 'Hello World'; 
15 echo CONSTANT;//Hello World

3. Combined comparison operators ()

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

 1 //整数 
 2 echo 1  1; // 0 
 3 echo 1  2; // -1 
 4 echo 2  1; // 1 5  
 6 //浮点数 7 echo 1.5  1.5; // 0 
 8 echo 1.5  2.5; // -1 
 9 echo 2.5  1.5; // 1 
 11 //字符串12 echo "a"  "a"; // 0
 13 echo "a"  "b"; // -1
 14 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

 1 //... 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. 
 2 function intSum(int ...$ints){ 
 3     return array_sum($ints); 
 4 } 
 5 var_dump(intSum(2,'3.5'));//5 
 6  
 7 //严格模式 
 8 //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  
 9 declare(strict_types=1);
 10 function add(int $a,int $b){
 11     return $a+$b;
 12 }
 13 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)

1 //有效的返回类型
2 declare(strict_types = 1);
3 function getInt(int $value): int {
4   return $value;
5 }
6 print(getInt(6));//6

1 //无效返回类型
2 declare(strict_types = 1);
3 function getNoInt(int $value): int {
4   return $value+'2.5';
5 }
6 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 an anonymous object.

 1 <?php  
 2 //php7以前 接口实现 
 3 interface User{ 
 4     public function getDiscount(); 
 5 } 
 6 class VipUser implements User{ 
 7     //折扣系数 
 8     private $discount = 0.6; 
 9     public function getDiscount() {
 10         return $this->discount;
 11     }
 12 }
 13 class Goods{
 14     private $price = 200;
 15     private $objectVipUser;
 16     //User接口VipUser类实现
 17     public function getUserData($User){
 18         $this->objectVipUser = $User;
 19         $discount = $this->objectVipUser->getDiscount();
 20         echo "商品价格:".$this->price*$discount;
 21     }
 22 }
 23 $display = new Goods();
 24 //常规实例化接口实现对象
 25 $display ->getUserData(new VipUser);//商品价格:120

 1 <?php  
 2 //php7 创建一个匿名的对象 
 3 interface User{ 
 4     public function getDiscount(); 
 5 } 
 6 class Goods{ 
 7     private $price = 200; 
 8 private $objectVipUser; 
 9     public function getUserData($User){
 10         $this->objectVipUser = $User;
 11         $discount = $this->objectVipUser->getDiscount();
 12         echo "商品价格:".$this->price*$discount;
 13     }
 14 }
 15 $display = new Goods();
 16 //new匿名对象实现user接口
 17 $display ->getUserData(new class implements User{
 18     private $discount = 0.6;
 19     public function getDiscount() {
 20         return $this->discount;
 21     }
 22 });//商品价格:120

7. Closure::call()

The Closure::call() method was added as a short way to temporarily bind a Scope the object to a closure and call it. Compared to PHP5's bindTo, its performance is much faster.

 1 <?php  
 2 //php7以前 
 3 class A { 
 4     private  $attribute = &#39;hello world&#39;; 
 5 } 
 6  
 7 $getClosure = function(){ 
 8     return $this->attribute; 
 9 };
 10 
 11 $getAttribute = $getClosure->bindTo(new A, 'A');//中间层闭包
 12 echo $getAttribute();//hello world

 1 <?php  
 2 //PHP7 
 3 class A { 
 4     private  $attribute = &#39;hello world&#39;; 
 5 } 
 6  
 7 $getClosure = function(){ 
 8     return $this->attribute; 
 9 };
 10 
 11 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

 1 <?php  
 2 class A{  
 3    public $name = &#39;admin_a&#39;;    
 4 } 
 5 class B{ 
 6    public $name = &#39;admin_b&#39;; 
 7 } 
 8  9 $objA = new A(); 
10 $objB = new B(); 
11 12 $serializedObjA = serialize($objA); 
13 $serializedObjB = serialize($objB); 
14 15 16 //默认行为是接收所有类; 第二个参数可以忽略17 $dataA = unserialize($serializedObjA , ["allowed_classes" => true]); 
18 var_dump($dataA);//object(A)#3 (1) { ["name"]=> string(7) "admin_a" }19 20 //如果allowed_classes设置为false,unserialize会将所有对象转换为__PHP_Incomplete_Class对象 21 $dataA = unserialize($serializedObjA , ["allowed_classes" => false]); 
22 var_dump($dataA);//object(__PHP_Incomplete_Class)#4 (2) { ["__PHP_Incomplete_Class_Name"]=> string(1) "A" ["name"]=> string(7) "admin_a" }23 24 //转换所有对象到 __PHP_Incomplete_Class对象，除了对象"B"25 $dataB = unserialize($serializedObjB , ["allowed_classes" => ["B"]]); 
26 var_dump($dataB);//object(B)#3 (1) { ["name"]=> string(7) "admin_b" }

9. IntlChar

##IntlChar: Provides some Access to utility methods for accessing Unicode character information. NOTE: The Intl extension must be installed to use!

1 var_dump(IntlChar::CODEPOINT_MAX);//int(1114111) 
2 echo '<br>';
3 var_dump(IntlChar::charName('+'));//string(9) "PLUS SIGN" 
4 echo '<br>';
5 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() - Cryptographically protected pseudo-random integer.

1 $bytes = random_bytes(8); 
2 echo(bin2hex($bytes));//随机2073a110a2e3c497
3 echo '<br>';
4 echo(random_int(1, 999));//随机786
5 echo '<br>';
6 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.

 1 //PHP7之前 
 2 use some\namespace\ClassA; 
 3 use some\namespace\ClassB; 
 4 use some\namespace\ClassC as C; 
 5 use function some\namespace\fn_a; 
 6 use function some\namespace\fn_b; 
 7 use function some\namespace\fn_c; 
 8 use const some\namespace\ConstA; 
 9 use const some\namespace\ConstB;
 10 use const some\namespace\ConstC;
 11 
 12 // PHP7之后
 13 use some\namespace\{ClassA, ClassB, ClassC as C};
 14 use function some\namespace\{fn_a, fn_b, fn_c};
 15 use const some\namespace\{ConstA, ConstB, ConstC};

12. intp

The newly added intp() function receives two parameters, and the return value is the value of the first parameter divided by the second parameter and rounded

.

1 echo intp(8,4);//2
2 echo intp(10,4);//2
3 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.

 1 <?php  
 2 //php7以前 自定义异常处理 
 3 class getException extends Exception{ 
 4     public function errorMsg(){ 
 5         return &#39;错误的信息&#39;.$this->getMessage().'<br>错误的代码'.$this->getCode(); 
 6     } 
 7 } 
 8  
 9 try {
 10     $num =10;
 11     if($num > 1) {
 12         throw new getException($num,404);
 13     }
 14 } catch (getException $e) {
 15     echo $e->errorMsg();
 16 }

1 <?php   
2 //php7 异常处理
3 try {
4     test();
5 }catch(Error $e) {
6     echo $e->getMessage();//Call to undefined function test()
7 }

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