PHP7.1 new features

1. Nullable type

The types of parameters and return values can now be allowed to be empty by adding a question mark before the type. When this feature is enabled, the parameters passed in or the result returned by the function are either the given type or null

#php5
function($a = null){
  if($a===null) {
    return null;
  }
  return $a;
}

#php7+
function fun() :?string
{
  return null;
}

function fun1(?$a)
{
  var_dump($a);
}
fun1(null);//null
fun1('1');//1

2. void type

return value Methods declared as void may simply omit the return statement. For void, NULL is not a legal return value.

function fun() :void
{
  echo "hello world";
}

3. Class constant visibility

class Something
{
    const PUBLIC_CONST_A = 1;
    public const PUBLIC_CONST_B = 2;
    protected const PROTECTED_CONST = 3;
    private const PRIVATE_CONST = 4;
}

4. iterable pseudo class

This can be used in parameters or In the return value type, it represents an object that accepts an array or implements the Traversable interface.

function iterator(iterable $iter)
{
    foreach ($iter as $val) {
        //
    }
}

5. Multiple exception capture processing

One catch Statement blocks can now capture multiple exceptions through the pipe character (_|_). This is useful when you need to handle different exceptions from different classes at the same time

try {
    // some code
} catch (FirstException | SecondException $e) {
    // handle first and second exceptions
}

6. List supports key names

$data = [
    ["id" => 1, "name" => 'Tom'],
    ["id" => 2, "name" => 'Fred'],
];

// list() style
list("id" => $id1, "name" => $name1) = $data[0];
var_dump($id1);//1

7. String supports negative direction

$a= "hello";
$a[-2];//l

8. Convert callback to closure

Closure has added a new static method to quickly convert callable into a Closure object.

<?php
class Test
{
    public function exposeFunction()
    {
        return Closure::fromCallable([$this, &#39;privateFunction&#39;]);
    }

    private function privateFunction($param)
    {
        var_dump($param);
    }
}

$privFunc = (new Test)->exposeFunction();
$privFunc('some value');

9. http2 service push

Support for http2 server push has now been added to the CURL extension

Original link: https:// cloud.tencent.com/dev...

New features of PHP7.2

New object type

This new object type,object, introduces any object type that can be used for contravariant parameter input and covariant return.

<?php

function test(object $obj) : object
{
    return new SqlQueue();
}

test(new Stdclass());

Allow overriding of abstract methods

When an abstract class inherits from another abstract class, the inherited abstract class can override the abstraction of the inherited abstract class. method.

<?php

abstract class A
{
    abstract function test(string $s);
}

abstract class B extends A
{
    abstract function test($s) : int;
}

Use the Argon2 algorithm to generate password hashes

Argon2 has been added to the password hashing API (these functions start with password_), the following are the exposed constants:

PASSWORD_ARGON2I
PASSWORD_ARGON2_DEFAULT_MEMORY_COST
##PASSWORD_ARGON2_DEFAULT_TIME_COST
PASSWORD_ARGON2_DEFAULT_THERADS

Allow trailing commas for grouped namespaces

Namespaces can be introduced in PHP 7 using trailing commas for grouping.

<?php

use Foo\Bar\{
    Foo,
    Bar,
    Baz,
};

PHP7.3 new features

1 Release time

06 Dec 2018

Official website PHP7.3 new features

2 Update Flexible

Heredoc `and` Nowdoc `syntax The`

closing tag no longer needs to stand on its own line or be followed by a semicolon. At the same time, the closing tag can also use indentation. When indentation is used, each line of the doc content will skip the corresponding indentation.

$data = ["元素", <<<STR
    Doc Content
    The new line
    STR, 42,];
var_dump($data);

array(3) {
  [0]=>
  string(6) "元素"
  [1]=>
  string(25) "Doc Content
The new line"
  [2]=>
  int(42)
}

In the above syntax, Heredoc appears as an array element, and the closing tag is not on a separate line and is indented. Note that in the defined string content, the indentation of both lines has been stripped.

3 Array destruction supports reference assignment

Demonstration:

$v = [10, 20];
[$a, &$b] = $v;
$b += 10;
var_dump($v, $a, $b);

array(2) {
  [0]=>
  int(10)
  [1]=>
  &int(30)
}
int(10)
int(30)

When parsing $b, reference passing is used, at this time $b and $v[1] Elements maintain reference relationships.

4 The list structure supports reference resolution.

Demonstration:

$v = [10, 20];
list($c, &$d) = $v;
$d += 10;
var_dump($v, $c, $d);

array(2) {
  [0]=>
  int(10)
  [1]=>
  &int(30)
}
int(10)
int(30)

5 The instanceof operator supports literal syntax

The first operand of instanceof supports literals, and the result of non-object literal detection is false .

var_dump("literal" instanceof stdClass);
var_dump(42 instanceof stdClass);
var_dump(new stdClass() instanceof stdClass);

bool(false)
bool(false)
bool(true)

6 Support trailing commas for parameters when calling

When calling a function, a comma is allowed after the parameter list.

function methodName($p1, $p2)
{
    // some statmenet
    var_dump($p1, $p2);
}
methodName(10, 20, );

int(10)
int(20)

When calling a function, adding a comma after the second (last) parameter is allowed. But the definition doesn't work.

7 BC mathematical function

bcscale()The function supports obtaining the scale used by the current BC function.

bcscale(3);
var_dump(bcscale());

int(3)

8 LDAP full support

LDAP: Lightweight Directory Access Protocol, lightweight directory access protocol is fully supported.

9 Multi-byte string function update

Case-insensitive string operators use Case -Folding
Support Unicode 11
Long string support
Named capture support

10 FastCGI process management

Added The following options are used to configure FPM Logging: (not yet translated)

log_buffering
decorate_workers_output

11 Argon2id Algorithm support

--with-password-argon2[=dir] after configuring parameters. Provided support for Argon2i and Argon2id hashes in Password_*() functions. Use the PASSWORD_ARGON2ID constant to specify the algorithm. PHP requires the libargon2 library version to be greater than (equal to) 20161029.

12 CompileError exception replaces some compilation errors

A new CompileError exception is added, and ParseError inherits this exception. Currently only affects compilation errors that may be caused by Token_GET_All() in Token_parse mode.

13 Performance improvement

It is said that PHP7.3 is 22% faster than PHP 7.0. Not tested yet, give it a stress test if you have a chance.

14 废弃大小写不敏感的常量

大小写不敏感的常量声明现已被废弃。将 TRUE 作为第三个参数传递给 define() 会导致一个废弃警告。大小写不敏感的使用（在读取时使用一个与声明时不同的大小写方式）也已被废弃。

15 废弃在字符串中搜索非字符串内容

将一个非字符串内容传递给字符串搜索函数。在将来所有待搜索的内容都将被视为字符串，而不是 ASCII 编码值。如果需要依赖这个特性，你应该要么显示地进行类型转换（转为字符串），或者显示地调用 chr()。以下是受到影响的方法：

16 新常量

新常量

原文链接：https://zhuanlan.zhihu.com/p/...

PHP7.4新特性

1、预加载

预加载功能是指在服务启动时，未运行任何应用程序代码之前，将一组PHP文件加载到内存中，甚至可以对框架进行预加载，以提高性能。如果对预加载代码进行修改，需要重启服务。

预加载相比opcache：opcache虽然解决了重复编译问题，但opcache本身也有开销。引用Dmitry Stogov大佬的话：

Not only. The idea is to completely eliminate compilation and opcache overhead (copying from SHM to process memory and insertions into function/class tables on each request). Using this technique, we might write standard functions and classes in PHP (similar to systemlib.php in HHVM).
预加载是完全消除编译和opcache所带来的开销（从共享内存复制到进程内存，并在每个请求上插入到function/class表中），使用这种技术可以在PHP中编写标准函数和类（类似于HHVM中的systemlib.php）

想想看，其实预加载主要是提升像php-fpm这种架构形式的性能，并且会占用更多的内存资源。Benjamin Morel对预加载进行了测试。

https://github.com/composer/composer/issues/7777#issuecomment-440268416

使用方法：

通过修改php.ini中的opcache.preload来选择预加载程序。使用方法如下：

php.ini

[opcache]
zend_extension=opcache.so
opcache.enable=1
opcache.enable_cli=1
opcache.preload=preload.php

preload.php

<?php 

function preload()
{
    echo &#39;preload&#39;;
}

opcache_compile_file(&#39;hello.php&#39;);

hello.php

<?php 

function hello()
{
    echo &#39;hello&#39;;
}

test.php

<?php

hello();
echo &#39; &#39;;
preload();
echo PHP_EOL;

运行

~$ php test.php
hello preload

2、FFI

有时间我们再聊，先占上位置。

3、类属性的类型支持

php版本<7.4：

<?php

class User
{
    /** @var int $id */
    private $id;

    /** @var string $name */
    public $name;
}

php版本>=7.4：

<?php

class User
{
    private int $id;

    public string $name;
}

一个完整的示例：

<?php

class Example {
    // 支持除了“void”和“callable”之外的所有类型
    public int $scalarType;
    protected ClassName $classType;
    private ?ClassName $nullableClassType;
 
    // 在静态属性中也是合法的
    public static iterable $staticProp;
 
    // 也可以与“var”一起使用
    var bool $flag;
 
    // 也可以使用默认值
    public string $str = "foo";
    public ?string $nullableStr = null;
 
    // 在一次声明多个属性的情况下，类型会作用于各属性。
    public float $x, $y;
    // 相当于这样:
    public float $x;
    public float $y;
}

以下是支持的所有类型：

bool, int, float, string, array, object
iterable
self, parent
class interface // 任何 类名、接口名
?type // 其中“type”可以是以上任意一种类型

4、NULL合并赋值运算符

写法：$a ??= 1 。其实就是 $a = $a ?? 1 的语法糖。

例子：

<?php

$arr[&#39;a&#39;] ??= &#39;a&#39;;
/*等同于*/ $arr[&#39;a&#39;] = $arr[&#39;a&#39;] ?? &#39;a&#39;; 

$b ??= &#39;b&#39;; 
/*等同于*/ $b = $b ?? &#39;b&#39;;

5、弃用WDDX扩展

我相信大多数人和我一样并不了解wddx，wddx是一个很“古老”的数据格式，基于xml（emmm，可能我理解的不是很对，大概其就是这个意思吧）。现在都在用json，所以弃用了也罢。有兴趣的童鞋可以看一下这篇文章。

https://blog.csdn.net/guoguo1980/article/details/2436342

6、简化匿名函数

此特性就是一个语法糖，相信你在别的语言中也见到过，下面是一些例子：

<?php

$adder = fn($x, $y) => $x + $y;

// 等同于

$adder = function ($x, $y) {
    return $x + $y;
};

/*******************************/

$y = 1;
$fn1 = function ($x) use ($y) {
    return $x + $y;
}; 

// 等同于

$fn2 = fn($x) => $x + $y;

// 新的写法省去了 use, 变得更加简洁

更多用法：

<?php

fn(array $x) => $x;          // 参数类型声明
fn(): int => $x;             // 返回类型声明
fn($x = 42) => $x;           // 参数默认值
fn(&$x) => $x;               // 引用传递
fn&($x) => $x;               // 引用返回
fn($x, ...$rest) => $rest;   // 变长参数

其实我个人不是很赞同php引入那么多语法糖，这使得php的语法变得越来越复杂，关于此rfc的投票，鸟哥选择了反对，包括韩天峰大佬也对此特别反对，php应该回归初心——简单高效。

7、新增mb_str_split函数

mb_str_split是mbstring扩展中新增的一个函数，通过函数名就可以猜到，它是str_split函数的“增强版（多字节处理）”，它的作用和str_split一样，都是将字符串拆分成数组，只是增加了第三个参数，用于设置字符编码。

说明：

mb_str_split ( string $string [, int $split_length = 1, string $encoding = mb_internal_encoding() ] ) : array

例子：

<?php
print_r(mb_str_split("PHP是世界上最好的语言", 3));

// Array
// (
//     [0] => PHP
//     [1] => 是世界
//     [2] => 上最好
//     [3] => 的语言
// )

// 也可以指定编码
print_r(mb_str_split("PHP是世界上最好的语言", 3, "GB2312"));

8、始终可用的Hash扩展

从PHP7.4开始，Hash扩展是PHP核心扩展，无法通过--disable-hash禁用，因此它始终可用。

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