CODEWITHSUNDEEP
phprecursion
Tom
Tom

Reputation: 224

How do I store the results of this recursive function?

I have the following PHP code which works out the possible combinations from a set of arrays:

function showCombinations($string, $traits, $i){

    if($i >= count($traits)){

        echo trim($string) . '<br>';

    }else{

        foreach($traits[$i] as $trait){
            showCombinations("$string$trait", $traits, $i + 1);
        }

    }

}

$traits = array(
            array('1','2'),
            array('1','2','3'),
            array('1','2','3')
            );

showCombinations('', $traits, 0);

However, my problem is that I need to store the results in an array for processing later rather than just print them out but I can't see how this can be done without using a global variable.

Does anyone know of an alternative way to achieve something similar or modify this to give me results I can use?

Upvotes: 5

Views: 2723

Answers (6)

Kapil Gautam
Kapil Gautam

Reputation: 1

public function pageslug_genrator($slug,$cat){


     $page_check=$this->ci->cms_model->show_page($slug);

      if($page_check[0]->page_parents != 0 ){

      $page_checks=$this->ci->page_model->page_list($page_check[0]->page_parents);
      $cat[]=$page_checks['re_page'][0]->page_slug;
      $this->pageslug_genrator($page_checks['re_page'][0]->page_slug,$cat);    

      }
    else
        {
       return $cat;

       }
  }

this function doesnt return any value but when i m doing print_r $cat it re

Upvotes: 0

user187291
user187291

Reputation: 53950

although the solution by Lukáš is the purest as it has no side effects, it may be ineffective on large inputs, because it forces the engine to constantly generate new arrays. There are two more ways that seem to be less memory-consuming

  • have a results array passed by reference and replace the echo call with $result[]=
  • (preferred) wrap the whole story into a class and use $this->result when appropriate

the class approach is especially nice when used together with php iterators

Upvotes: 0

Dereleased
Dereleased

Reputation: 10087

Using the variable scope modifier static could work. Alternatively, you could employ references, but that's just one more variable to pass. This works with "return syntax".

function showCombinations($string, $traits, $i){
    static $finalTraits;
    if (!is_array($finalTraits)) {
        $finalTraits = array();
    }
    if($i >= count($traits)){

        //echo trim($string) . '<br>';
        $finalTraits[] = $string;

    } else {

        foreach($traits[$i] as $trait){
            showCombinations("$string$trait", $traits, $i + 1);
        }

    }
    return $finalTraits;
}

$traits = array(
            array('1','2'),
            array('1','2','3'),
            array('1','2','3')
            );

echo join("<br>\n",showCombinations('', $traits, 0));

Of course, this will work as expected exactly once, before the static nature of the variable catches up with you. Therefore, this is probably a better solution:

function showCombinations($string, $traits, $i){
    $finalTraits = array();
    if($i >= count($traits)){
        $finalTraits[] = $string;
    } else {
        foreach($traits[$i] as $trait){
            $finalTraits = array_merge(
                               $finalTraits,
                               showCombinations("$string$trait", $traits, $i + 1)
                               );
        }
    }
    return $finalTraits;
}

Upvotes: 0

agscala
agscala

Reputation: 3865

In addition to the other answers, you could pass the address of an array around inside your function, but honestly this isn't nearly the best way to do it.

Upvotes: 1

Luk&#225;š Lalinsk&#253;
Luk&#225;š Lalinsk&#253;

Reputation: 41316

Return them. Make showCombinations() return a list of items. In the first case you only return one item, in the other recursive case you return a list with all the returned lists merged. For example:

function showCombinations(...) {
    $result = array();
    if (...) {
        $result[] = $item;
    }
    else {
        foreach (...) {
            $result = array_merge($result, showCombinations(...));
        }
    }
    return $result;
}

Upvotes: 11

dnagirl
dnagirl

Reputation: 20446

store the results in a $_SESSION variable.

Upvotes: -1

Related Questions