PHP recursive function output

Question

With the following code:

$array = array(
    'id' => '1',
    'parent_id' => '0',
    'name' => 'top level',
    'children' => array(
        'id' => '2',
        'parent_id' => '1',
        'name' => 'second level',
        'children' => array(
            'id' => '3',
            'parent_id' => '2',
            'name' => 'third level'     
        )
    )
);

function generateFlatArray($array){

  $output .= '[select id="' . $array['id'] . '" name="' . $array['name'] . '"]';

  if(is_array($array['children'])){
    generateFlatArray($array['children']);
  }

  return $output;

}

print_r(generateFlatArray($array));

Why does this output:

[select id="1" name="top level"]

and not what I am expecting, which is:

[select id="1" name="top level"][select id="2" name="second level"][select id="3" name="third level"]

I hate recursion. I hate recursion. I hate recursion. Thanks.

Tim · Accepted Answer · 2014-04-13 10:57:53Z

2

You did not use the return value of the function, only the first $output is used.

function generateFlatArray($array){

   $output .= '[select id="' . $array['id'] . '" name="' . $array['name'] . '"]';

   if(is_array($array['children'])){
     $output .= generateFlatArray($array['children']);
   }

   return $output;
}

answered Apr 13, 2014 at 10:57

Tim

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Comments

Niet the Dark Absol · Accepted Answer · 2014-04-13 10:57:34Z

1

Because you aren't doing anything with the return value of the recursive steps.

$output .= generateFlatArray($array['children']);

That's what I think you want.

answered Apr 13, 2014 at 10:57

Niet the Dark Absol

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Comments

Blizz · Accepted Answer · 2014-04-13 10:57:48Z

1

Because you have to append the output during the recursive call as well:

if(is_array($array['children'])){
    $output .= generateFlatArray($array['children']);
}

answered Apr 13, 2014 at 10:57

Blizz

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