# PHP重点新特性

1. 文件上传进度 session.upload\_progress
2. short\_open\_tag 无论是否开启，都可用
3. 动态访问静态变量
4. 异常可以嵌套
5. const 关键字可用来在类定义之外定义常量了
6. Heredoc 结构中可以用双引号来声明标识符了
7. 添加 Nowdoc 语法支持
8. 增加 goto 操作符
9. 后期静态绑定
10. default\_charset从ISO-8859-1已经变为UTF-8
11. 新增了动态访问静态方法的方式 , 5.4
12. 内置用于开发的 CLI 模式的 web server
13. 实例化时访问类成员 (new Foo)->bar();
14. 对函数返回数组的成员访问解析 print func()\[0];
15. 新增二进制直接量 $bin = 0b110011;
16. boolval() 函数
17. 新增 array\_column() 函数
18. 直接通过下标获取访问数组和字符串字面量的元素或字符
19. empty() 支持传入一个任意表达式，而不仅是一个变量,5.3不行,5.5之後可以
20. foreach 支持 list()
21. 新增 finally 关键字
22. 新增 Traits
23. 函数返回值类型声明,标量类型声明

更多新特性，请访问我的另外一本gitbook: <https://php.shujuwajue.com/>

## 示例:

3.动态访问静态变量

```php
class C {
    public static $foo = 123;
}

$a = "C";
echo $a::$foo;
```

18.直接通过下标获取访问数组和字符串字面量的元素或字符

```php
echo [1,2,3][0]; // 1
echo 'hello world'[0]; // h
```


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