匿名函数

获取可变长度参数

<?php

  function check_func()
  {
      var_dump(func_get_args());
  	  //输出:['www','check','net'];
      echo func_get_arg(1),"<br>";
  	  //输出:check
      echo func_num_args();
  	  //输出:3
  }

check_func("www", "check", "net");

匿名函数

将函数名的字符串赋值给变量,变量加上括号就可以执行.

use引用外部变量

<?php
  $str = "this_is_str";
  $num = 666;
  $a = function () use ($str,&$num)
  {
      echo $str; 
      echo $num; 
      var_dump(func_get_args());
  };
  $a("www", "check", "net");

类型约束:出参入参

<?php

function text_out_para(int $num):int
{
    return $num;
}
echo text_out_para(111);//111
echo text_out_para("eee");
//Argument 1 passed to text_out_para() must be of the type int;
//Argument 1 passed to text_out_para() must be of the type int