返回内部 PHP 递归 function

Question

I am writing a PHP recursive function to get data using their value form an array. So here is function what I am trying to build:

  function test($menu) {

    $url = "test.com/accounts/overview/";

    foreach($menu as $data) {

      if( is_array($data) and array_key_exists("t_link", $data) and $data["t_link"] === $url ) {

        return $data["t_icon"]; 

      } else if(is_array($data)) {

        test($data);

      }
    }
  }

echo test($menu);

The first condition only true for one time as of my array and the return must return the value & terminate the function, isn't it?. But why it is noting return? Also, if I use echo $data["t_icon"]; instead of return $data["t_icon"]; it is showing the correct result: fa fa-book .

This is the array from where I am trying to get the t_icon value based on the t_link value. The condition is if t_link value has test.com/accounts/overview/ then it will return the fa fa-book

$menu = array ();
$menu["Dashboard"] = array (
    "t_link"    => "test.com",
    "t_icon"    => "fa fa-dashboard"
  );
  $menu["Accounts"] = array (
    "t_link"    => "test.com/accounts",
    "t_icon"    => "fa fa-books"
  );
  $menu["Accounts"]["Overview"] = array (
    "t_link"    => "test.com/accounts/overview/",
    "t_icon"    => "fa fa-book"  <<-- This value I want to get
  );

I searched a lot of and got this that I should return the function inside the second condition like this return test($data); . But it also not working. Thank you.

Answer 1

Because you call a function inside a function, you have to return the value of the function, here is the fix: (added "return" before test($data);)

 function test($menu) {

    $url = "test.com/accounts/overview/";

    foreach($menu as $data) {

      if( is_array($data) and array_key_exists("t_link", $data) and $data["t_link"] == $url ) {
        return $data["t_icon"]; 
      } else if(isset($data["Overview"])) {
        return test($data);
      }
    }
  }

Also, all three cases, they both array so return test($data); will stop the foreach then $menu["Accounts"]["Overview"] will never be check.

Answer 2

Your code is not working because a function should always have a return value - in recursion it is required :

function test($menu) {

    $url = "test.com/accounts/overview/";

    foreach($menu as $data) {

      if( is_array($data) && 
      isset($data["t_link"]) && 
      $data["t_link"] === $url ) {        
          return $data["t_icon"]; 
      } 
      else if (is_array($data)) {
          $result = test($data); //Get result back from function

          //If it's NOT NULL call the function again (test($data))
          //
          //(down below returns null when looped through 
          //everything recursively)
          //
          if ($result !== null) { 
              return $result;
          }
      }

    }

    return null;
}

---

Here's another way of achieving what you want OOP-style:

The idea behind this solution is to create a two-level array (no more, no less nr of levels) and grab data from that new array.

class Searcher {
    private $new_arr = array();
    private $icon = '';

    //array_walk_recursive goes through your array recursively
    //and calls the getdata-method in the class. This method creates
    //a new array with strings (not arrays) from supplied $array ($menu in your case)
    public function __construct($array, $search_url) {
        array_walk_recursive($array, array($this, 'getdata'));     
        $key = array_search($search_url, $this->new_arr['t_link']);
        $this->icon = $this->new_arr['t_icon'][$key];
    }

    public function geticon() {
        return $this->icon;
    }

    public function getdata($item, $key) {
        if (!is_array($item)) {
            $this->new_arr[$key][] = $item;    
        }        
    }

}

//Implementation (usage) of above class
$search = new Searcher($menu, 'test.com/accounts/overview/');
$icon = $search->geticon();
echo 'ICON=' . $icon; //Would echo out 'fa fa-book'

Further explanation:

Based on your $menu - array the class will create an array like this ( $this->new_arr ):

Array
(
    [t_link] => Array
        (
            [0] => test.com
            [1] => test.com/accounts
            [2] => test.com/accounts/overview/
        )

    [t_icon] => Array
        (
            [0] => fa fa-dashboard
            [1] => fa fa-books
            [2] => fa fa-book
        )

)

---

All the keys are related to eachother in the new array. This is set with $this->new_arr[$key][] = $item;within the getdata() method. This is based on the fact it must be equal number of t_link -keys and t_icon -keys in the array.

Because of this:

$this->new_arr[0]['t_link'] is related to $this->new_arr[0]['t_icon'];
$this->new_arr[1]['t_link'] is related to $this->new_arr[1]['t_icon'];
$this->new_arr[2]['t_link'] is related to $this->new_arr[2]['t_icon'];
etc.. (not more in your example)

---

When having this code:

$key = array_search($search_url, $this->new_arr['t_link']);

it would give the key 2 if you have supplied $search_url to test.com/accounts/overview/

Therefore:

$this->icon = $this->new_arr['t_icon'][$key];

is set to fa fa-book