CODEWITHSUNDEEP
phpfunctioncallself-reference
Andrei Surdu
Andrei Surdu

Reputation: 2341

Recursive function: Call php function itself

I just want to make sure I do it right and this will not create any conficts.

I have a function which calls itself and need your approval if it's OK or not to do so?

<?php

function determine($the_array){
    foreach ($the_array as $key => $value) {
        switch ($key) {
            case 'in':
                    echo $value;
                break;

            case 'out':
                    echo $value;
                break;

            case 'level':
                    echo '<ul>';
                    determine($value);
                    echo '</ul>';
                break;

        }
    }

}

This is the array:

$the_array = array(
    'in' => '<li>Simple IN</li>',
    'out' => '<li>Simple OUT</li>',
    'level' => array(
            'in' => '<li>Simple IN 2</li>',
            'out' => '<li>Simple OUT 2</li>',
            'level' => array(
                'in' => '<li>Simple IN 3</li>',
                'out' => '<li>Simple OUT 3</li>'
            ),
        ),
);

And here is the final init: 

echo '<ul>';
determine($the_array);
echo '</ul>';

The result is just how I wanted to be, it works great, but I don't know if this is a good practice.

Upvotes: 16

Views: 31366

Answers (4)

Fluffeh
Fluffeh

Reputation: 33512

Recursive functions are OK - but dangerous if you aren't sure you know what you are doing. If there is any chance that a function will end up in a recursive loop (where it keeps calling itself over and over) you will either time out, run out of memory or cause a zombie apocalypse.

Think of recursive calls as a really, really sharp knife - in the hands of an experienced chef, it's a match made in heaven, in the hands of the dishwasher, it is a lost finger waiting to happen.

PHP tries to play nice, and limits a recursive depth to 100 by default (though this can be changed) but for almost all cases, if your recursive depth gets to 100, the accident has already happened and PHP reacts by stopping any additional pedestrians from wandering into traffic. :)

Upvotes: 45

T.Todua
T.Todua

Reputation: 56391

I dont know, if it's a good solution, but i use this one to call a function from inside itself:

function my_calucar(){
    $arrayy= array('mine' => '1',  'yours' => '24', 'her' => '34');
    foreach ($arrayy as $each=>$value) {
        switch ($each) {
        default:
                my_calucar($value);
        }
    }
}

Upvotes: 1

MD SHAHIDUL ISLAM
MD SHAHIDUL ISLAM

Reputation: 14523

I think if you know depth of array it is good to use

$list = "";
foreach ($the_array as $array) {
    if(is_array($array)) {
       foreach($array as $sub_array) {
          if(is_array($sub_array)) {
              foreach($sub_array as $sub_array_2) {
                  $list .= "$sub_array_2";
               }
          } else {
             $list .= "$sub_array";
          }
       }
    } else {
        $list .= "$array";
    }
}

echo "<ul>$list</ul>";

Upvotes: 0

Kleskowy
Kleskowy

Reputation: 2668

Fluffeh provided sufficient answer as far as recursive functions are concerned. But when using recursion with large arrays/objects/etc, you should watch optimisation of your code, so that it doesn't take much memory or CPU power to execute.

You could easily optimise your code to be cleaner, take less memory and be more resilient to unexpected data. Notice the & in the function arguments list (it eliminates creating a copy of an array everytime a nested function is called).

function determine(& $the_array){
foreach ($the_array as $key => $value) {
    switch ($key) {
        case 'in':
        case 'out':
                echo $value;
            break;

        case 'level':
            if (!is_array($value)) break;
                echo '<ul>';
                determine($value);
                echo '</ul>';
            break;

        }
    }
}

Upvotes: 3

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