Can you store a function in a PHP array?

The recommended way to do this is with an anonymous function:

$functions = [
  'function1' => function ($echo) {
        echo $echo;
   }
];

If you want to store a function that has already been declared then you can simply refer to it by name as a string:

function do_echo($echo) {
    echo $echo;
}

$functions = [
  'function1' => 'do_echo'
];

In ancient versions of PHP (<5.3) anonymous functions are not supported and you may need to resort to using create_function (deprecated since PHP 7.2):

$functions = array(
  'function1' => create_function('$echo', 'echo $echo;')
);

All of these methods are listed in the documentation under the callable pseudo-type.

Whichever you choose, the function can either be called directly (PHP ?5.4) or with call_user_func/call_user_func_array:

$functions['function1']('Hello world!');

call_user_func($functions['function1'], 'Hello world!');

what you mean its call : Passing by Reference

its very simple like

function changearray(&$arr){
     $arr['x'] = 'y';
}

you can call this like :

changearray($_SESSION);

I hadn't noticed that you edited your question, which changes things entirely. You have two decent options here:

1. Explicitly change them at the top of the function:

   function foo($bar, &$baz, &$qux) {
       $baz = $qux = array();
   }
   

2. Perhaps this is a good place to introduce an object?

   class parseConfig {
       protected $rawXml;
       protected $configName;
       protected $radioArr   = array();
       protected $flasherArr = array();
       protected $irdArr     = array();
   
       public function __construct($raw_xml = null) {
           if (!is_null($raw_xml)) {
               $this->rawXml = $raw_xml;
               $this->parse();
           }
       }
   
       public function parse($raw_xml = null) {
           if (!is_null($raw_xml)) {
               $this->rawXml = $raw_xml;
           }
   
           if (empty($this->rawXml)) {
               return null;
           }
   
           $this->configName = '';
           $this->radioArr   =
           $this->flasherArr =
           $this->irdArr     = array();
   
           // parsing happens here, may return false
   
           return true;
       }
   
       public function setRawXml($raw_xml) {
           $this->rawXml = $raw_xml;
           return $this;
       }
   
       public function getRawXml() {
           return $this->rawXml;
       }
   
       public function getRadioArr() {
           return $this->radioArr;
       }
   
       public function getFlasherArr() {
           return $this->flasherArr;
       }
   
       public function getIrdArr() {
           return $this->irdArr;
       }
   }