• 引用参数

$name = "eko";function chang_name(&$name){    $name .= '_after_change';}    chang_name($name);    //会改变原有参数$nameecho $name;

• 参数类型声明

function test(array $arr){    for ($i=0; $i 
     
      ';    }}test('hello'); 报错interface Animal {    function eat();    function sleep();}class Cat implements Animal{    public function eat(){        echo "cat eat fish";    }    public function sleep(){        echo "cat is sleeping";    }}function fn(Animal $animal){    echo $animal -> eat();}fn(new Cat());
     

• 可变参数

function fn(){    $arg_nums = func_num_args();　　//获得参数个数    echo "此时传入 $arg_nums 个参数";    echo "
";    $arr_args = func_get_args();    //获得所有参数，返回数组    echo gettype($arr_args) ."
";   //输出array    foreach ($arr_args as $arg) {        echo $arg."
";    }    $arg = func_get_arg(0);        //获得第0个参数    echo $arr_arg;}fn('hello',123);

//在PHP5.6以上版本中，可以用拓展运算符代替可变参数function fn(...$args){    echo "input ".count($args)." arguments";    echo '
';    for ($i=0; $i 
     
      ';    }}fn('hello','word',123);fn(...['hello','word',123]); //结果同上//如果有多个参数，可变参数必须放在最后function fn($name,...$args){    echo $name .'
      
';    for ($i=0; $i 
      
       ';    }}fn('kitty','yellow','miao');
      
     

• 返回类型

//php7 中支持函数返回值类型声明function sum(...$args):int{    $sum = 0 ;    foreach ($args as $value) {        $sum += $value;    }    return $sum;    //return 'hello'; //报错，Return value of sum() must be of the type integer}echo sum(1,2,3,4,5);

• 匿名函数 (闭包函数 Closure)

echo preg_replace_callback('~-([a-z])~', function ($match) {    return strtoupper($match[1]);}, 'hello-world');//输出 helloWorld