数组
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PHP手册

数组 函数

参见

参考 is_array(), explode(), implode(), split(), preg_split(), and unset().

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数组
在线手册：中文 英文
PHP手册
PHP手册 - N: 数组 函数

用户评论:

topor-grabowski at viversum dot de (05-Apr-2012 05:53)

If your searching for a function that is deleting all elements in an array with the same value here is it.
I was searching for something like that but did not find it.
Hope you will like it and use it.

<?php

//deletes all $array entries with $valueToDelete as element value; does function recursive
//without changing original array
public static function array_delete_elements($array = null, $valueToDelete = null) {
  //no array given
  if (!isset($array)) {
    return null;
  }
  //process
  $resultList = array();
  foreach ($array as $entryKey => $entryValue) {
    if (is_array($entryValue)) {
      //entry is array and should be handled again recursive
      $resultList[$entryKey] = array_delete_elements($entryValue, $valueToDelete);
    } else {
      if ($entryValue != $valueToDelete) {
        $resultList[$entryKey] = $entryValue;
      }
    }
  }
  return $resultList;
}

?>

dave at davidhbrown dot us (24-Sep-2011 07:57)

While PHP has well over three-score array functions, array_rotate is strangely missing as of PHP 5.3. Searching online offered several solutions, but the ones I found have defects such as inefficiently looping through the array or ignoring keys.

The following array_rotate() function uses array_merge and array_shift to reliably rotate an array forwards or backwards, preserving keys. If you know you can trust your $array to be an array and $shift to be between 0 and the length of your array, you can skip the function definition and use just the return expression in your code.

<?php
function array_rotate($array, $shift) {
    if(!is_array($array) || !is_numeric($shift)) {
        if(!is_array($array)) error_log(__FUNCTION__.' expects first argument to be array; '.gettype($array).' received.');
        if(!is_numeric($shift)) error_log(__FUNCTION__.' expects second argument to be numeric; '.gettype($shift)." `$shift` received.");
        return $array;
    }
    $shift %= count($array); //we won't try to shift more than one array length
    if($shift < 0) $shift += count($array);//handle negative shifts as positive
    return array_merge(array_slice($array, $shift, NULL, true), array_slice($array, 0, $shift, true));
}
?>
A few simple tests:
<?php
$array=array("foo"=>1,"bar"=>2,"baz"=>3,4,5);

print_r(array_rotate($array, 2));
print_r(array_rotate($array, -2));
print_r(array_rotate($array, count($array)));
print_r(array_rotate($array, "4"));
print_r(array_rotate($array, -9));
?>

Nitrogen (13-Sep-2010 04:17)

I made a simple little function to make an array (containing readable data) presentable in human form.
I added some error checking, too.. (if it's not human-readable, don't include it).
<?php
function Combine($Input) {
  if(!is_array($Input)) // I only want arrays.
    return(false);

  // remove named index (only numeric index)
  $Input=array_values($Input);

  // read the array, if it's not a string or number, remove it!
  for($i=0;$i<count($Input);$i++)
    if(!is_string($Input[$i])&&!is_numeric($Input[$i]))
      unset($Input[$i]);

  // if an element got removed in the middle of the array, it leaves holes in the
  // array index, so we use array_values to reset them again.
  $Input=array_values($Input);

  // several array counts used asead.
  $Count=count($Input);

  if($Count>1)
    return(implode(', ',array_splice($Input,0,$Count-1)).' and '.$Input[0]);
  if($Count==1)
    return($Input[0]);
  if($Count==0)
    return('');
  // nothing should happen beyond this point.
}

Combine(array('A')); // A
Combine(array('A','B')); // A and B
Combine(array('A','B','C')); // A, B and C
Combine(array('A','B','9',4,5)); // A, B, 9, 4 and 5
Combine(array(3,false,5,'nine','?!?!')); // 3, 5, nine and ?!?!
// and so on...

?>

Hope this helps someone,
Nitrogen.

oliverSPAMMENOT at e-geek dot com dot au (23-Mar-2010 03:28)

Function to pretty print arrays and objects. Detects object recursion and allows setting a maximum depth. Based on arraytostring and u_print_r from the print_r function notes. Should be called like so:

<?php
egvaluetostring($value)   //no max depth, or
egvaluetostring($value, $max_depth)   //max depth set

function egvaluetostring($value, $max_depth, $key = NULL, $depth = 0, $refChain = array()) {
  if($depth > 0)
    $tab = str_repeat("\t", $depth);
  $text .= $tab . ($key !== NULL ? $key . " => " : "");
 
  if (is_array($value) || is_object($value)) {
    $recursion = FALSE;
    if (is_object($value)) {
      foreach ($refChain as $refVal) {
        if ($refVal === $value) {
          $recursion = TRUE;
          break;
        }
      }
      array_push($refChain, $value);
    }
   
    $text .= (is_array($value) ? "array" : "object") . " ( ";
   
    if ($recursion) {
      $text .= "*RECURSION* ";
    }
    elseif (isset($max_depth) && $depth >= $max_depth) {
      $text .= "*MAX DEPTH REACHED* ";
    }
    else {
      if (!empty($value)) {
        $text .= "\n";
        foreach ($value as $child_key => $child_value) {
          $text .= egvaluetostring($child_value, $max_depth, (is_array($value) ? "[" : "") . $child_key . (is_array($value) ? "]" : ""), $depth+1, $refChain) . ",\n";
        }
        $text .= "\n" . $tab;
      }
    }
   
    $text .= ")";
   
    if (is_object($value)) {
      array_pop($refChain);
    }
  }
  else {
    $text .= "$value";
  }

  return $text;
}
?>

ducnm0 at gmail dot com (01-Mar-2010 01:08)

A function to convert php array into JS object, supporting both object and array:

<?php
static function is_assoc($array) {
        foreach ( array_keys ( $array ) as $k => $v ) {
            if ($k !== $v)
                return true;
        }
        return false;
    }
   
    static function arrayPHPToJS($data) {
        if (is_null($data)) return 'null';
        if (is_string($data)) return "'" . $data . "'";
        if (self::is_assoc($data)) {
            $a=array();
            foreach ($data as $key => $val )
                $a[]="'" . $key . "' :" .self::arrayPHPtoJS($val);
            return "{" . implode ( ', ', $a ) . "}";
        }
        if (is_array($data)) {
            $a=array();
            foreach ($data as $val )
                $a[]=self::arrayPHPtoJS($val);
            return "[" . implode ( ', ', $a ) . "]";
        }
        return $data;
    }
?>

phektus at gmail dot com (02-Dec-2009 11:44)

This is how I solved my array combinations problem. My particular situation is that I needed to project combinations of certain results and analyse each combination based from a consolidation of one of their attributes. The following example does not show the analysis part but it shows how I came up with my combinations ($traits).

This is actually an improvement on: http://ask.metafilter.com/64554/Finding-combinations-in-PHP
as it deals with arrays of strings, while I need to combine arrays within an array (you guessed it, database results).

Hope somebody finds this useful or teaches me a simpler way [by email] to do this. Public domain etc.

<?php
    header('Content-Type: text/plain');
   
    class Test {
        // holds the combinations
        var $combinations= array();               
   
        function getCombinations($batch, $elements, $i)  {
            if ($i >= count($elements)) {
                $this->combinations[] = $batch;
            } else {     
                foreach ($elements[$i] as $element) {
                    $this->getCombinations(array_merge($batch, $element), $elements, $i + 1);
                }                       
            }
        }
    }       
   
   
    // Test it!
   
    $traits = array (
        array(
            array('Happy'),
            array('Sad'),
            array('Angry'),
            array('Hopeful')
        ),
        array(
            array('Outgoing'),
            array('Introverted')
        ),
        array(
            array('Tall'),
            array('Short'),
            array('Medium')
        ),
        array(
            array('Violent'),
            array('Quiet'),
            array('Psychotic')
        ),
        array(
            array('Handsome'),
            array('Plain'),
            array('Ugly')
        )
    );

    $test = new Test();
    $start = array();
    $test->getCombinations($start, $traits, 0);   
    print_r($test->combinations);           
   
?>

shadiadiph at yahoo dot com (01-Nov-2009 03:24)

This is a useful function to remove an array value from an array.

<?php

function rem_array($array,$str){
foreach ($array as $key => $value) {
if ($array[$key] == "$str") unset($array[$key]);
}
return $array;
}

$selected='';
$selected ="three";
$numbers=array();
$numbers=array('one','two','three','four');
print_r($numbers);

// returns  Array ( [0] => one [1] => two [2] => three [3] => four )

// now we are going to call the function to see if the number three the $selected number is in the array $numbers and remove it.

$numbers = rem_array($numbers,$selected);

print_r ($numbers);
// returns  Array ( [0] => one [1] => two [3] => four )

?>

I am finding it usefull for drop down lists on forms where you do not want the selected value duplicated.

seva dot lapsha at gmail dot com (03-Aug-2009 02:22)

Arrays are good, but inapplicable when dealing with huge amounts of data.

I'm working on rewriting some array functions to operate with plain Iterators - map, reduce, walk, flip et cetera are already there.

In addition I'm going to implement simulation of comprehensions (generators) in PHP (http://en.wikipedia.org/wiki/List_comprehension).

See the source code, examples and documentation at http://code.google.com/p/php-iterator-utils/

jan at hooda dot de (07-Dec-2008 11:49)

Two simple functions to add and delete values from arrays:

<?php
      function array_add (&$array, $val) {
        array_push ($array, $val);
      }

      function array_del (&$array, $str)
      {
        if (in_array($str,$array)==true) {
          foreach ($array as $key=>$value) {
            if ($value==$str) unset($array[$key]);
          }
        }
      } 
?>

renatonascto at gmail dot com (17-Sep-2008 07:11)

Big arrays use a lot of memory possibly resulting in memory limit errors. You can reduce memory usage on your script by destroying them as soon as you?re done with them. I was able to get over a few megabytes of memory by simply destroying some variables I didn?t use anymore.
You can view the memory usage/gain by using the funcion memory_get_usage(). Hope this helps!

pragash_jey at yahoo dot com (06-Apr-2008 03:38)

Java Like Array Implementation!

<?php
/*
 * Author : Pragash Jeyaratnam
 * Vector Class
 * PHP Version 5.2.5
 * Contact : pragash_jey@yahoo.com.
 */
class Vector
{
    /*
     * The number of valid components in this Vector object.
     */
    protected $elementCount;
    /*
     * The array buffer into which the components of the vector are stored.
     */
    protected $elementData;
   
   
         
    /**Default vector Constructor*/
    function __construct()
    {
        $this->elementData = array();
        $this->elementCount = count($this->elementData);
    }
   
   
   
    /**Append the parameter element to the vector*/
    public function add($object)
    {
        if(!empty($object))
        {
            $this->elementData[] = $object;
            $this->elementCount = count($this->elementData);
            return true;
        }
        else
            return false;
           
    }
   
    /*
     * Returns true of Vector is empty false otherwise
     */
    public function isEmpty()
    {
        return($this->elementCount==0);
    }
   
   
  /*
   * Returns the current size of this Vector
   */
   public function size()
   {
       return $this->elementCount;
   }
   
   /*
    *  Searches for the first occurence of the given argument
    **/
   public function indexOf($object)
   {
          if(($index =array_search($object,$this->elementData)) !==false)
              return $index;
          else
              return -1;
   }
  
   /*
    * This function will retain TRUE if $object is contained
    * within the vector else FALSE
    */
  
   public function contains($object)
   {
           return ($this->indexOf($object)>=0);
   }
   
   /*
    * Returns Vector Object at index $index
    * Error : Null is returned
    */
     
   public function get($index)
   {
           if($this->checkBound($index))
           {
               return ($this->elementData[$index]);
           }
           return NULL;
   }
  
   /*
    * Sets the object at $index to be $object
    **/
  
   public function set($index,$object)
   {
           if($this->checkBound($index))
           {
               $this->elementData[$index] =$object ;
               return true;
           }
           return false;
   }
  
  /*
   * Removes element at $index
   **/
  
      public function removeAt($index)
      {
       if ($this->checkBound($index))
           {
                 for ($i = $index; $i != $this->elementCount - 1; $i++)
                  {
                   $this->elementData[$i] = $this->elementData[$i +1];
             }
       array_pop($this->elementData);
       $this->elementCount = count($this->elementData);
           
       return true;
       }
       else {
            return false;
            }
      }
   
    /**
     * Removes all elements from the Vector.  Note that this does not
     * resize the internal data array.
     */
   public function removeAll()
   {
         if($this->elementCount ==0)
             return;
         for($i=0;$i<$this->size();$i++)
         {
             $this->set($i,NULL);
         }
   }
   
   
   /*
    * This function checks whether index
    * is within the array bound
    **/
  
   private function checkBound($index)
   {
         if($index > $this->elementCount-1 || $index < 0)
         {
             throw new Exception('Array Index Out Of Bound Exception');
             return false;
         }
         return true;
   }
  
    /*
     *Removes the first element from the Vector
     */
   
    public function removeFirstElement()
    {
        if($this->elementCount==0)
        {
            throw new Exception('No Such Element');
        }
        $test =array_shift($this->elementData);
        if(!empty($test))
            $this->elementCount = count($this->elementData);
    }
  
}
?>

Anonymous (29-Mar-2008 07:28)

This is the shorter way to flatten a array:
<?php
  function array_flatten($a) {
    foreach($a as $k=>$v) $a[$k]=(array)$v;
    return call_user_func_array(array_merge,$a);
  }
?>

bas at muer dot nl (17-Mar-2008 04:17)

I see a lot of people here writing complex functions to convert an array to a string, for use with Javascript or other things (possibly even databases, which would be bad).
For Javascript, the most efficient way would be JSON (http://www.php.net/json_encode). For normal use, serialize() (http://www.php.net/serialize) is your friend.

jake at blah dot inf (07-Mar-2008 02:03)

@margol:

<?php
$tuple_array = array(array('key1' => 'val1'), array('key2' => 'val2'));
list($key, $val) = each(array_pop($tuple_array));
?>

But, why not use a two element array instead of a single-element associative array?

<?php
$tuple_array = array(array('key1', 'val1'), array('key2','val2'));
list($key,$val) = array_pop($tuple_array);
?>

margol at beamartyr dot net (04-Mar-2008 09:45)

More intuitive tuple support would be nice  :)

But for those scratching their heads, like I did, to extract a tuple from an array of tuples, do something like:

    $tuple = array_pop($tuple_array);
    $key = key($tuple);
    $val = $tuple[$key];

yousefomar (a) yahoo dot com (28-Feb-2008 07:26)

Here is how you refresh the expiration time for multiple cookies:

// get the cookie names
$keys=array_keys($_COOKIE);

// loop through all the cookies and update the exp. time
for ($i=0; $i<count($_COOKIE);$i++)
   setcookie( $keys[$i], $_COOKIE[$keys[$i]], time()+3600);

you can use this in authentication validate file to keep the session up.

ms419 at freezone dot co dot uk (14-Feb-2008 06:35)

This function takes an array, a key and a value. If the key is not an array, it acts just like $array[$key] =& $value; If the key is an array, it recurses in the array, creating nested arrays as necessary.

Example:

$array = array('A' => array('B' => 'phi'));
$key = array('A', 'Z');
$value = 'gamma';

arraySet($array, $key, $value);

$array should now be:

array('A' => array('B' => 'phi', 'C' => 'gamma'));

This is useful for constructing nested arrays from sets of filesystem paths (e.g. 'A/B/C') or structured variable names (e.g. 'A.B.C' or 'A[B][C]')

Example:

arraySet($array, preg_split('/\//', $path, -1, PREG_SPLIT_NO_EMPTY), $value);

function arraySet(array &$array, $key, &$value)
{
    if (is_array($key)) {
        $keyComponent = array_shift($key);

        if (empty($key)) {
            $array[$keyComponent] =& $value;
            return;
        }

        if (!is_array($array[$keyComponent])) {
            $array[$keyComponent] = array();
        }

        PHP_CodeSniffer_arraySet($array[$keyComponent], $key, $value);
        return;
    }

    $array[$key] =& $value;
}

dennis at DONTSPAMME dot born05 dot nl (13-Feb-2008 03:22)

I haven't completely figured out when or why an array gets referenced or copied, but it gave me quite the headache..

So i wrote a function which recursively copies an array while preserving keys and also clones objects if encountered

<?php
    /**
     * make a recursive copy of an array
     *
     * @param array $aSource
     * @return array    copy of source array
     */
    function array_copy ($aSource) {
        // check if input is really an array
        if (!is_array($aSource)) {
            throw new Exception("Input is not an Array");
        }
       
        // initialize return array
        $aRetAr = array();
       
        // get array keys
        $aKeys = array_keys($aSource);
        // get array values
        $aVals = array_values($aSource);
       
        // loop through array and assign keys+values to new return array
        for ($x=0;$x<count($aKeys);$x++) {
            // clone if object
            if (is_object($aVals[$x])) {
                $aRetAr[$aKeys[$x]]=clone $aVals[$x];
            // recursively add array
            } elseif (is_array($aVals[$x])) {
                $aRetAr[$aKeys[$x]]=array_copy ($aVals[$x]);
            // assign just a plain scalar value
            } else {
                $aRetAr[$aKeys[$x]]=$aVals[$x];
            }
        }
       
        return $aRetAr;
    }
?>

I hope i can save someone else's aspirine with this ;)

csorfab at gmail dot com (06-Feb-2008 06:26)

Here's a function I wrote to combine the values in an array in all different ways, and which returns a two-dimensional array as a byref result.

E.g.

if called:
comb(array(1, 2, 3), $r);

then $r would be:

1 2 3
1 3 2
2 1 3
2 3 1
3 1 2
3 2 1

<?php

    function comb($arr, &$rarr, $vtemp = array()){   
        foreach($arr as $key => $value){
            $vtemp2 = $vtemp;
            $vtemp2[] = $value;

            $atemp = $arr;           
            unset($atemp[$key]);
           
            if(count($atemp) > 0){
                comb($atemp, $rarr, $vtemp2);
            } else {
                $t = array();
           
                foreach($vtemp2 as $val){
                    $t[] = $val;
                }
               
                $rarr[] = $t;
            }
        }
    }

?>

christian dot reinecke at web dot de (02-Feb-2008 09:12)

Here are two more functions handling string2array and access array by string. It's useful if you want to access an array in xpath-style, such as parse_ini_file return values with $process_sections = TRUE.

<?php
function createArrayByString($string, $separator, $value = NULL)
{
    if (strlen($string) > 0) {
        $splitter = explode($separator, $string);
        $index = array_shift($splitter); // get first element
        $function = __FUNCTION__;
        return array($index => $function(implode($separator, $splitter), $separator, $value));
    }
    return $value;
}

function accessArrayByString($array, $string, $separator, $default = NULL)
{
    if (!is_array($array)) {
        return empty($string) ? $array : $default;
    }
    @list ($key, $rest) = explode($separator, $string, 2); // @ needed for last access
   
    $function = __FUNCTION__;
    return array_key_exists($key, $array)
         ? $function($array[$key], $rest, $separator, $default)
         : $default;
}

$string = "one.two.three.four";
$separator = ".";

$array = createArrayByString($string, $separator, "standard value");
$return = accessArrayByString($array, $string, $separator, "element not found");

var_dump($array); // should return array("one" => array("two" => array("three" => array("four" => "standard value"))))
var_dump($return); // should return "standard value";
?>

change the function name to what ever you want, the recursive call uses __FUNCTION__ for re-call.

florian at egliselasauzaie dot fr (30-Jan-2008 10:09)

I've created a class which is comparable to a Vector in C++;
<?php
class Vector {
    public $nb_elements;
    public $liste;

    public function Vector() {
        $this->liste = array ();
        $this->nb_elements = count($this->liste);
    }

    public function push_back($valeur) {
        if (!empty ($valeur)) {
            $this->liste[] = $valeur;
            $this->nb_elements = count($this->liste);
            return true;
        } else {
            return false;
        }
    }
    public function insert_at($indice, $valeur) {
        if ($indice > 0 && $indice < $this->nb_elements) {
            for ($i = $this->nb_elements; $i != $indice; $i--) {
                $this->liste[$i] = $this->liste[$i -1];
            }
            $this->liste[$indice] = $valeur;
            $this->nb_elements = count($this->liste);
            return true;
        } else {
            return false;
        }
    }
    public function remove_at($indice) {
        if ($indice > 0 && $indice < $this->nb_elements) {
            for ($i = $indice; $i != $this->nb_elements - 1; $i++) {
                $this->liste[$i] = $this->liste[$i +1];
            }
            array_pop($this->liste);
            $this->nb_elements = count($this->liste);
            return true;
        } else {
            return false;
        }
    }
    public function pop() {
        $value = array_pop($this->liste);
        $this->nb_elements = count($this->liste);
        return $value;
    }
    public function shift() {
        $value = array_shift($this->liste);
        $this->nb_elements = count($this->liste);
        return true;
    }
}
?>

really quick function (25-Jan-2008 08:37)

function array_flatten($a){ //flattens multi-dim arrays (distroys keys)
    $ab = array(); if(!is_array($a)) return $ab;
    foreach($a as $value){
        if(is_array($value)){
            $ab = array_merge($ab,array_flatten($value));
        }else{
            array_push($ab,$value);
        }
    }
    return $ab;
}

Jck_true (leave out the &#39;_&#39; at gmail dot com) (25-Jan-2008 10:00)

A usefull function that returns a flat array.
I use it in a template system. Let the user pass a multidimensional array. Convert it using my function. Then use
<?php
$array = flatten($array,'','{$','}','->');
echo str_replace(array_keys($array),array_values($array),$template)
/**
* Flattens out an multidimension array
* Using the last parameters you can define the new key based on the old path.
* @param array $array A multidimension array
* @param string $prefix Internal perfix parameter - leave empty.
* @param string $start_string What string should start the final array key?
* @param string $end_string What string should end the final array key?
* @param string $seperator The string that should seperate the piecies in final array key path
* @return array Returns the flat array
*/
function flatten($array, $start_string= '{$',$end_string= '}',$seperator='->',$prefix="") {
  $return = array();
  foreach($array as $key=>$value) {
    if (is_array($value)) {
      $return = array_merge($return, Parser_method_replace::flatten($value, $prefix.$key.$seperator,$start_string,$end_string,$seperator));
    } else
      $return [$start_string.$prefix.$key.$end_string] = $value;
  }
  return $return;
}
}
?>
Example:
$template = 'My string with replacement {$test->subkey}';
{$test->subkey} will get replaced with $array['test']['subkey']

chaos dot global dot net at gmail dot com (02-Jan-2008 11:53)

if some one will need to convert array to php code use this function:

DEFINE('OFFSET_DELIMETER', "\t");

function array2php($array, $offset = OFFSET_DELIMETER)  {
    $text = '';
    foreach($array as $k => $v) {
        if (is_array($v)) {
            $text .= "{$offset}'{$k}' => array(\n".array2php($v, $offset.OFFSET_DELIMETER)."$offset)";
        } else {
            $text .= "{$offset}'{$k}' => ".(is_string($v)? "'$v'": $v);
        }
        $text .= ",\n";
    }
    if ($len = strlen($text)) $text[$len - 2] = " ";
    return $text;
}

Hayley Watson (17-Oct-2007 12:10)

Regarding cyberchrist at futura dot net's function. It makes an unnecessary array_merge(); the elements of $b that are merged with those of $a are immediately removed again by the array_diff(). The "limiting to known values" is entirely unnecessary, in other words: arrays already only contain "known values".

Also, the description and function only address the issue of whether $a is a subset of $b, not whether it is a proper subset. For $a to be a proper subset of $b, it must also be the case that $b is not a subset of $a.

Taking those points into account (and a personal aesthetic dislike of "if(test) return true; else return false;" gives:

<?php
function is_subset($a, $b)
{
    return count(array_diff($a,$b))==0;
}

function is_proper_subset($a, $b)
{
    return is_subset($a, $b) && !is_subset($b, $a);
}
?>

cyberchrist at futura dot net (15-Oct-2007 02:33)

Lately, dealing with databases, I've been finding myself needing to know if one array, $a, is a proper subset of $b.

Mathematically, this is asking (in set theory) [excuse the use of u and n instead of proper Unicode):
 
( A u B ) n ( ~ B )

What this does is it first limits to known values, then looks for anything outside of B but in the union of A and B (which would be those things in A which are not also in B).

If any value exists in this set, then A is NOT a proper subset of B, because a value exists in A but not in B.  For A to be a proper subset, all values in A must be in B.

I'm sure this could easily be done any number of ways but this seems to work for me.  It's not got a lot of error detection such as sterilizing inputs or checking input types.

// bool array_subset( array, array )
// Returns true if $a is a proper subset of $b, returns false otherwise.

function array_subset( $a, $b )
{
    if( count( array_diff( array_merge($a,$b), $b)) == 0 )
        return true;
    else
        return false;
}

Kazuyoshi Tlacaelel (30-Aug-2007 07:56)

<?php
/**
 * converts a multidimensional array to a flat array
 *
 * trying to keep the original names of the keys
 * if repeated keys are found a hash will be added to the
 * keys trying to keep as much as possible of the original
 * key context
 *
 * september 30 2007
 *
 * PHP version 5
 *
 * @license         GPL
 *
 */

$array = array ( 0 => array ( 0 => 1, 1 => 2, 2 => array ( 0 => 3, 1 => 4, 2 =>
array ( 0 => 5, 1 => 6, 2 => array ( 0 => 7, 1 => 8,),),), 3 => array (
    0 => array ( 0 => 9, 1 => 10, 2 => array ( 0 => 11, 1 => 12,
    2 => array ( 0 => 13, 1 => 14, 2 => array ( 0 => 15, 1 => 16,),),),),
    1 => array ( 0 => 17, 1 => 18,),),), 1 => array ( 0 => 19, 1 => 20,),
    2 => array ( 0 => array ( 0 => 21, 1 => 22, 2 => array ( 0 => 23, 1 => 24,
    2 => array ( 0 => 25, 1 => 26, 2 => array ( 0 => 27, 1 => 28,),),),),
    1 => array ( 0 => 29, 1 => 30,),),);

/**
 * transforms a multidimensional array to a flat array
 *
 * the parameter is referenced
 * so no returning value is needed
 * @param array $array the multidimensional array to flat
 * @return void
 */
function array_flatten(&$array)
{
    function has_arrays($array)
    {
        foreach ($array as $item) {
            if (is_array($item)) {
                return true;
            }
        }
        return false;
    }

    function copy_array(&$array, $array_key)
    {
        $array2 = $array[$array_key];
        unset($array[$array_key]);
        foreach ($array2 as $subkey => $subvalue) {
            if (array_key_exists($subkey, $array)) {
                $array[generate_unique_key($subkey)] = $subvalue;
            } else {
                $array[$subkey] = $subvalue;
            }
        }
    }

    function generate_unique_key($key)
    {
        if (strlen($key)>8) {
            $key = $key[0] . $key[1] . $key[2];
        }
        $id = $key . '_';
        $uid = uniqid();
        $len = strlen($uid);
        $max = (9 - strlen($key));
        for ($c = $len; ; $c --) {
            $id .= $uid[$c];
            if ($c == ($len - $max)) {
                break;
            }
        }
        return $id;
    }

    function get_array_indexes($array)
    {
        $ret_array = array();
        foreach ($array as $key => $value) {
            if (is_array($value)) {
                $ret_array[] = $key;
            }
        }
        return $ret_array;
    }

    while(has_arrays($array)) {
        foreach (get_array_indexes($array) as $key) {
            copy_array($array, $key);
        }
    }
}

    array_flatten($array);
    array_multisort($array);
    var_export($array);

    /**
     *  OUTPUT
     *
     *  array (
     *    0 => 1,
     *    '1_403767b6' => 2,
     *    '0_793767b6' => 3,
     *    '1_8a3767b6' => 4,
     *    '0_454767b6' => 5,
     *    '1_564767b6' => 6,
     *    '0_035767b6' => 7,
     *    '1_345767b6' => 8,
     *    '0_e74767b6' => 9,
     *    '1_f84767b6' => 10,
     *    '0_855767b6' => 11,
     *    '1_a65767b6' => 12,
     *    '0_4e5767b6' => 13,
     *    '1_6f5767b6' => 14,
     *    '0_566767b6' => 15,
     *    '1_876767b6' => 16,
     *    '0_5b4767b6' => 17,
     *    '1_6c4767b6' => 18,
     *    '0_d43767b6' => 19,
     *    1 => 20,
     *    '0_4e3767b6' => 21,
     *    '1_5f3767b6' => 22,
     *    '0_ad4767b6' => 23,
     *    '1_ce4767b6' => 24,
     *    '0_485767b6' => 25,
     *    '1_695767b6' => 26,
     *    '0_116767b6' => 27,
     *    '1_426767b6' => 28,
     *    '0_814767b6' => 29,
     *    '1_924767b6' => 30,
     *  )
     */
?>

mo dot longman at gmail dot com (31-Jul-2007 07:27)

to 2g4wx3:
i think better way for this is using JSON, if you have such module in your PHP. See json.org.

to convert JS array to JSON string: arr.toJSONString();
to convert JSON string to PHP array: json_decode($jsonString);

You can also stringify objects, numbers, etc.

g4wx3 (19-Jul-2007 10:16)

I needed a function to convert a php array into a javascript array.
No problem i found it on "the net".

But the function i found wasn't good enough, instead of return a string with javascript-array it echoed directly everything.
I wanted to write the string to a file, when calling the function out of my function libary.

Secondly, there where minor "bugs" in the script, when you're original array contained characters like line breaks(\r\n,..), or quotes('), it would hack up the javascript array

Sow, i changed the function and fixed the bug.

<?php
//SUPER COOL : http://www.communitymx.com/content/article.cfm?page=3&cid=7CD16
//Checkout:  REVERSE: http://www.hscripts.com/tutorials/php/jsArrayToPHP.php
//Convert a PHP array to a JavaScript one (rev. 4)
//Changlog by g4wx3: echo replaced by $output, added function output
function output($string) //make javascript ready
    {
    $string = str_replace( array( '\\' , '\'' ), array('\\\\', '\\\'') , $string); //-> for javascript array
    $string = str_replace(  array("\r\n", "\r", "\n") , '<br>' , $string);    //nl2br
    return $string;
    }
function arrayToJS4($array, $baseName ) {
    //Write out the initial array definition
//v4    echo ($baseName . " = new Array(); \r\n ");
    $output = $baseName . " = new Array(); \r\n ";

    //Reset the array loop pointer
    reset ($array);

    //Use list() and each() to loop over each key/value
    //pair of the array
    while (list($key, $value) = each($array)) {
        if (is_numeric($key)) {
        //A numeric key, so output as usual
        $outKey = "[" . $key . "]";
        } else {
        //A string key, so output as a string
        $outKey = "['" . $key . "']";
        }
     
        if (is_array($value)) {
        //The value is another array, so simply call
        //another instance of this function to handle it
        $output .= arrayToJS4($value, $baseName . $outKey);
        } else {

            //Output the key declaration
//v4            echo ($baseName . $outKey . " = ");     
            $output .= $baseName . $outKey . " = ";
           
            //Now output the value
            if (is_string($value)) {
                //Output as a string, as we did before      
//v4                echo ("'" . output($value) . "'; \r\n ");
                $output .= "'" . output($value) . "'; \r\n ";
            } else if ($value === false) {
                //Explicitly output false
//v4                echo ("false; \r\n");
                $output .= "false; \r\n";
            } else if ($value === NULL) {
                //Explicitly output null
//v4                echo ("null; \r\n");
                $output .= "null; \r\n";
            } else if ($value === true) {
                //Explicitly output true
//v4                echo ("true; \r\n");
                $output .= "true; \r\n";
            } else {
            //Output the value directly otherwise
//v4            echo ($value . "; \r\n");
            $output .= $value . "; \r\n";
            }
        }
    }
return $output;
}
?>
You can use this for printing $_GET array, for example

peanutpad at msn dot com (15-Jun-2007 11:15)

heres a function from http://www.linksback.org  Feedback welcome, of course!  Public domain, yadda yadda.

function mySort(&$array,$key) {
    if (!is_array($array) || count($array) == 0) return true;
    $assocSortCompare  = '$a = $a["'.$key.'"]; $b = $b["'.$key.'"];';

    if (is_numeric($array[0][$key])) {
      $assocSortCompare.= ' return ($a == $b) ? 0 : (($a < $b) ? -1 : 1);';
    } else {
      $assocSortCompare.= ' return strcmp($a,$b);';
    }

    $assocSortCompare = create_function('$a,$b',$assocSortCompare);
    return usort($array,$assocSortCompare);
}

webdev at svbeatrix dot com (11-Jun-2007 05:06)

Bugs happen, but how can people post functions that WON'T EVEN COMPILE!  I truly detest finding a cool code snippet or function and then having to debug them. Sorry for the rant, but I have experienced this scenario a number of times.  TEST YOUR CODE, THEN POST!

Here is a revised and corrected previously posted function ArrayDepth, which had 3 bugs and yes, would not compile.

function ArrayDepth($Array,$DepthCount=-1) {
// Find maximum depth of an array
// Usage: int ArrayDepth( array $array )
// returns integer with max depth
// if Array is a string or an empty array it will return 0
  $DepthArray=array(0);
  $DepthCount++;
  $Depth = 0;
  if (is_array($Array))
    foreach ($Array as $Key => $Value) {
      $DepthArray[]=ArrayDepth($Value,$DepthCount);
    }
  else
    return $DepthCount;
  return max($DepthCount,max($DepthArray));
}

sid dot pasquale at gmail dot com (29-May-2007 10:57)

<?php
/* This function allow you to transform a multidimensional array
   in a simple monodimensional array.
   Usage: array_walk($oldarray, 'flatten_array', &$newarray);
   For example, this code below shows to you:
        Array
        (
            [1] => Array
                (
                    [0] => 1
                    [1] => 2
                )
       
            [2] => Array
                (
                    [0] => 3
                    [1] => 4
                )
       
        )
       
        Array
        (
            [0] => 1
            [1] => 2
            [2] => 3
            [3] => 4
        )
*/

function flatten_array($value, $key, &$array) {
    if (!is_array($value))
        array_push($array,$value);
    else
        array_walk($value, 'flatten_array', &$array);
 
}
 
$oldarray = array(
    1 => array(1,2),
    2 => array(3,4)
);
$newarray = array();
array_walk($oldarray, 'flatten_array', &$newarray);
echo "<pre>";
print_r($oldarray);
print_r($newarray);
echo "</pre>";
?>

info at dyflexis dot nl (17-Apr-2007 09:13)

A modernized version of the flatten_array() functies written by

davidj at boundlessgallery dot DISLIKESPAM dot com
on 02-Apr-2004 03:10

This function is able to work with associative arrays

<?php
function flatten_array($array) {
     $size=sizeof($array);
     $keys=array_keys($array);
    for($x = 0; $x < $size; $x++) {
         $element = $array[$keys[$x]];

        if(is_array($element)) {
            $results = flatten_array($element);
                $sr = sizeof($results);
                $sk=array_keys($results);
            for($y = 0; $y < $sr; $y++) {
                $flat_array[$sk[$y]] = $results[$sk[$y]];
            }
        } else {
            $flat_array[$keys[$x]] = $element;
        }
    }

    return $flat_array;
}
?>

info at joolee dot nl (19-Mar-2007 12:49)

A slight modification in the arraytostring function, posted below. This function lists an array the same way you would define it in PHP.

<?PHP
function arraytostring($array, $depth = 0)
{
   if($depth > 0)
      $tab = implode('', array_fill(0, $depth, "\t"));
   $text.="array(\n";
   $count=count($array);

   foreach ($array as $key=>$value)
   {
       $x++;

       if (is_array($value))
       {
           if(substr($text,-1,1)==')')    $text .= ',';
           $text.=$tab."\t".'"'.$key.'"'." => ".arraytostring($value, $depth+1);
           continue;
       }

       $text.=$tab."\t"."\"$key\" => \"$value\"";

       if ($count!=$x) $text.=",\n";
   }

   $text.="\n".$tab.")\n";

   if(substr($text, -4, 4)=='),),')$text.='))';

   return $text;
}
?>

Vladson (14-Mar-2007 03:18)

Hope someone find it useful..

<?php
/*
    Function: eratosthenes
    Usage: array eratosthenes ( int max_value )

    Description:
    Sieve of Eratosthenes is a simple, ancient algorithm
    for finding all prime numbers up to a specified integer.
    It was created by Eratosthenes, an ancient Greek mathematician.
*/
function eratosthenes($max) {
    $sieve = array_fill(2, ($max-1), false);
    while ($key = array_search(false, $sieve)) {
        $sieve[$key] = true;
        for ($i=$key*$key; $i<=$max; $i+=$key) {
            if (array_key_exists($i, $sieve)) {
                unset($sieve[$i]);
            }
        }
    }
    return array_keys($sieve);
}
?>

aflavio at gmail dot com (01-Mar-2007 07:29)

/**
    * Remove a value from a array
    * @param string $val
    * @param array $arr
    * @return array $array_remval
    */
    function array_remval($val, &$arr)
    {
          $array_remval = $arr;
          for($x=0;$x<count($array_remval)-1;$x++)
          {
              $i=array_search($val,$array_remval);
              if($i===false)return false;
              $array_remval=array_merge(array_slice($array_remval, 0,$i), array_slice($array_remval, $i+1));
          }
          return $array_remval;
    }

$stack = array("orange", "banana", "apple", "raspberry", "apple");

output $stack = array("orange", "banana", "raspberry");

rune at zedeler dot dk (28-Feb-2007 04:42)

Notice that keys are considered equal if they are "=="-equal. That is:

<?
$a = array();
$a[1] = 'this is the first value';
$a[true] = 'this value overrides the first value';
$a['1'] = 'so does this one';
?>

Mark Lindeman (17-Jan-2007 10:10)

Very simple solution for changing the key of an associative array, of course it will fail in a lot of scenarios, but will do the trick in simple arrays:

<?php
function replace_key(&$input, $from_key, $to_key)
{
    $input = unserialize(str_replace(':"'.$from_key.'";', ':"'.$to_key.'";',serialize($input)));
}

$array =array("a"=>1, "B"=>2, "c"=>3);
replace_key($array, "B", "b");
print_r($array);
?>
Output:
Array
(
    [a] => 1
    [b] => 2
    [c] => 3
)

php_spam {at] erif dot org (28-Dec-2006 06:52)

public domain, yadda yadda. :)

This function takes a flatfile-like array (like the results of a joined query) and normalizes it based on whichever parameters you like.

<?php

  function hashByFields($things,$fields) {
    $retval=null;
    $count = count($fields);
    foreach ($things as $thing) {
      $fwibble =& $retval;
      for ($j=0;$j<$count;$j++) {
        $val = $thing[$fields[$j]];
        if ($j == $count - 1) {
          $fwibble[$val] = $thing;
        } else if (!isset($fwibble[$val])) {
          $fwibble[$val] = Array();
        }
        $fwibble =& $fwibble[$val];
      }
    }
    return $retval;
  }

?>

simone dot carletti at unimc dot it (28-Nov-2006 03:09)

Ever wanted to obtain a subset of an associative array from a list of parameters (stored into a non-associative array)?
Give this a try:

<?php

$params = array("name" => "Simone", "gender" => "M", "city" => "Macerata", "phone" => 123);
$fields = array("name", "city");

echo "<pre>";
print_r($params);
print_r($fields);
print_r(subArr($params, $fields));

function subArr($assocArrHaystack, $arrFields)
{
    $arrSub = array();

    foreach ($assocArrHaystack as $key => $value) {
        if (in_array($key, $arrFields)) {
            $arrSub[$key] = $value;
        }
    }

    return $arrSub;
}

?>

And the output is:

Array
(
    [name] => Simone
    [gender] => M
    [city] => Macerata
    [phone] => 123
)
Array
(
    [0] => name
    [1] => city
)
Array
(
    [name] => Simone
    [city] => Macerata
)

Enjoy!

Simone

elkabong at samsalisbury dot co dot uk (13-Nov-2006 11:43)

An improvement to the array_deep_copy function I posted ages ago which takes a 'snapshot' of an array, making copies of all actual values referenced... Now it is possible to prevent it traversing the tree forever when an array references itself. You can set the default $maxdepth to anything you like, you should never call this function with the $depth specified!
<?php
/* Make a complete deep copy of an array replacing
references with deep copies until a certain depth is reached
($maxdepth) whereupon references are copied as-is...  */
function array_deep_copy (&$array, &$copy, $maxdepth=50, $depth=0) {
    if($depth > $maxdepth) { $copy = $array; return; }
    if(!is_array($copy)) $copy = array();
    foreach($array as $k => &$v) {
        if(is_array($v)) {        array_deep_copy($v,$copy[$k],$maxdepth,++$depth);
        } else {
            $copy[$k] = $v;
        }
    }
}

# call it like this:

array_deep_copy($array_to_be_copied,$deep_copy_of_array,$maxdepth);
?>
Hope someone finds it useful!

ob at babcom dot biz (28-Aug-2006 04:18)

Regarding my own posting 2 postings down about the function ArrayDepth() to find the maximum depth of a multidimensional array:

A number of functions for counting array dimensions have been posted. And I tried using them. Yet, if at all they only return the depth of the first branch of the array. They can not handle arrays where a later path holds a more dimension than the first.

My version will check all paths down the array and return the maximum depth. That's why I posted it.

ob at babcom dot biz (28-Aug-2006 01:56)

Here are two functions Array2String() and String2Array() based on functions posted below by daenders AT yahoo DOT com.

An improvement handling NULL values correctly was posted by designatevoid at gmail dot com.

My version also solves the NULL-value-problem plus keeps support of multidimensional arrays.

<?php
// convert a multidimensional array to url save and encoded string
// usage: string Array2String( array Array )

function Array2String($Array) {
  $Return='';
  $NullValue="^^^";
  foreach ($Array as $Key => $Value) {
    if(is_array($Value))
      $ReturnValue='^^array^'.Array2String($Value);
    else
      $ReturnValue=(strlen($Value)>0)?$Value:$NullValue;
    $Return.=urlencode(base64_encode($Key)) . '|' . urlencode(base64_encode($ReturnValue)).'||';
  }
  return urlencode(substr($Return,0,-2));
}
?>

<?php
// convert a string generated with Array2String() back to the original (multidimensional) array
// usage: array String2Array ( string String)

function String2Array($String) {
  $Return=array();
  $String=urldecode($String);
  $TempArray=explode('||',$String);
  $NullValue=urlencode(base64_encode("^^^"));
  foreach ($TempArray as $TempValue) {
    list($Key,$Value)=explode('|',$TempValue);
    $DecodedKey=base64_decode(urldecode($Key));
    if($Value!=$NullValue) {
      $ReturnValue=base64_decode(urldecode($Value));
      if(substr($ReturnValue,0,8)=='^^array^')
        $ReturnValue=String2Array(substr($ReturnValue,8));
      $Return[$DecodedKey]=$ReturnValue;
     }
    else
      $Return[$DecodedKey]=NULL;
  }
  return $Return;
}
?>

ob at babcom dot biz (28-Aug-2006 12:23)

Here is a function to find out the maximum depth of a multidimensional array.

<?php
// return depth of given array
// if Array is a string ArrayDepth() will return 0
// usage: int ArrayDepth(array Array)

function ArrayDepth($Array,$DepthCount=-1,$DepthArray=array()) {
  $DepthCount++;
  if (is_array($Array))
    foreach ($Array as $Key => $Value)
      $DepthArray[]=ArrayDepth($Value,$DepthCount);
  else
    return $DepthCount;
  foreach($DepthArray as $Value)
    $Depth=$Value>$Depth?$Value:$Depth;
  return $Depth;
}
?>

ob at babcom dot biz (28-Aug-2006 12:18)

Regarding the function of spam at madhermit dot net from January 9th 2006:

That function only preserves the deepest keys and values.
If you try to flatten an array with that function where the deepest instance of keys might be the same where as keys in the "key-path" are different, values will be overwritten.

So here is a function that preserves the whole key-path and the keys of the flattened array will be string keys consisting of the key-path separated by $Separator.

<?php
// flatten multidimensional array to one dimension
// preserves keys by generating a key for the flattened array which consists of the
// key-path of the multidimensional array separated by $Separator
// usage: array ArrayFlatten( array Array [, string Separator] )

function ArrayFlatten($Array,$Separator="_",$FlattenedKey='') {
  $FlattenedArray=Array();
  foreach($Array as $Key => $Value) {
    if(is_Array($Value))
      $FlattenedArray=Array_merge($FlattenedArray,
                                  ArrayFlatten($Value,$Separator,
                                               (strlen($FlattenedKey)>0
                                                ?$FlattenedKey.$Separator
                                                :"").$Key)
                                               );
    else
      $FlattenedArray[$FlattenedKey.$Separator.$Key]=$Value;
  }
  return $FlattenedArray;
}
?>

sergio at {NO_SPAM_PLEASE]inservibile dot org (16-Aug-2006 01:17)

In a pratical problem, I was involved in a system of queries giving the behaviour of all combinations of some parameters. How to write those queries?
The problem was to generate automatically every possible combination of those parameters. I didn't find a function and I wrote it.
(Naturally, a different way could be to build a binary sequence, but I find this function more compact and useful).
So, consider an array of objects and suppose to need all possibile combinations of those objects. Here is the function, that could be useful for some folk.
Enjoy.

<?php
function combinations($elements) {
         if (is_array($elements)) {
            /*
            I want to generate an array of combinations, i.e. an array whose elements are arrays
            composed by the elements of the starting object, combined in all possible ways.
            The empty array must be an element of the target array.
            */
            $combinations=array(array()); # don't forget the empty arrangement!
            /*
            Built the target array, the algorithm is to repeat the operations below for each object of the starting array:
            - take the object from the starting array;
            - generate all arrays given by the target array elements merged with the current object;
            - add every new combination to the target array (the array of arrays);
            - add the current object (as a vector) to the target array, as a combination of one element.
            */
            foreach ($elements as $element) {
                    $new_combinations=array(); # temporary array, see below
                    foreach ($combinations as $combination) {
                            $new_combination=array_merge($combination,(array)$element);
                            # I cannot merge directly with the main array ($combinations) because I'm in the foreach cycle
                            # I use a temporary array
                            array_push($new_combinations,$new_combination);
                            }
                    $combinations=array_merge($combinations,$new_combinations);
                    }
            return $combinations;
            } else {
            return false;
            }
         }
?>

To test the function:

<?php
$elements=array('bitter','sour','salty','sweet');
print_r(combinations($elements));
?>

The exemple was suggested in 6th century BC.
See why on: http://en.wikipedia.org/wiki/Combinatorics#Overview_and_history

za at byza dot it (20-Jul-2006 04:52)

Updated functions for moving element between associative arrays using a numeric index.

Sample:
$a=array("04"=>"alpha",4=>"bravo","c"=>"charlie","d"=>"delta");
$b=array_move($a,4,2);

Move element "bravo" after "delta" keeping keys.
Old function probably goes wrong moving "alpha": caused by array_search that match numeric index 4 with "04" (string).

Follow:

<?php
// array functions - 20/07/2006 12.28

if(!defined("ARRAY_FUNCS")) {   
    // Swap 2 elements in array preserving keys.
    function array_swap(&$array,$key1,$key2) {
        $v1=$array[$key1];
        $v2=$array[$key2];
        $out=array();
        foreach($array as $i=>$v) {
            if($i===$key1) {
                $i=$key2;
                $v=$v2;
            } else if($i===$key2) {
                $i=$key1;
                $v=$v1;
            }
            $out[$i]=$v;
        }
        return $out;
    }
   
    //  Get a key position in array
    function array_kpos(&$array,$key) {
        $x=0;
        foreach($array as $i=>$v) {
            if($key===$i) return $x;
            $x++;
        }
        return false;
    }
   
    // Return key by position
    function array_kbypos(&$array,$pos) {
        $x=0;
        foreach($array as $i=>$v) {
            if($pos==$x++) return $i;
        }
        return false;
    }

    // Move an element inside an array preserving keys
    // $relpos should be like -1, +2...
    function array_move(&$array,$key,$relpos) {
        if(!$relpos) return false;
        $from=array_kpos($array,$key);
        if($from===false) return false;
        $to=$from+$relpos+($relpos>0?1:0);
        $len=count($array);
        if($to>=$len) {
            $val=$array[$key];
            unset($array[$key]);
            $array[$key]=$val;
        } else {
            if($to<0) $to=0;
            $new=array();       
            $x=0;
            foreach($array as  $i=>$v) {
                if($x++==$to) $new[$key]=$array[$key];
                if($i!==$key) $new[$i]=$v;
            }
            $array=$new;
        }
        return $array;
    }

    define("ARRAY_FUNCS",true);
}
?>

g8z at yahoo dot com (19-Jul-2006 09:42)

<?php
/**
filter_by_occurrence scans an array, and depending on the $exclusive parameter, includes or excludes elements occuring at least $min_occurences times, and at most $max_occurances times.

parameters:

$data_set = the array to work on
$min_occurrences = the minimum number of occurrences
$max_occurrences = the maximum number of occurrences (zero for unlimited)
$exclusive = if true, will return only results that do not occur within the specified bounds

Courtesy of the $5 Script Achive: http://www.tufat.com
**/

function filter_by_occurrence ($data_set, $min_occurrences, $max_occurrences = 0, $exclusive = false) {
    $results = array();

    // iterate through unique elements
    foreach (array_unique($data_set) as $value) {

        // count how many times element is in the array
        $count = 0;
        foreach ($data_set as $element) {
            if ($element == $value)
                $count++;
        }

        // check if meets min_occurences
        $is_in_range = false;

        if ($count >= $min_occurrences) {
            // check if meets max_occurrences (unless max_occurences is 0)
            if ( $count <= $max_occurrences || $max_occurrences == 0)
                $is_in_range = true;
        }

        // add item to array if appropriate
        if ($is_in_range && !$exclusive)
            array_push($results, $value);
        if (!$is_in_range && $exclusive)
            array_push($results, $value);
    }

    // return results
    return $results;
}

// EXAMPLE:

$test_data = array('pizza', 'ham', 'pizza', 'pizza', 'ham', 'fish', 'fish', 'fish', 'fish', 'dinosaur');

foreach (filter_by_occurrence( $test_data, 3, 0, false ) as $value)
{
    print $value . ' occurs at least 3 times. <br />';
}

?>

nick (11-Jul-2006 01:46)

This little function will move an array element up or down. Unlike the similar function in a previous comment this will work for associative arrays too.

Because it uses current to traverse the array it will fail if a value is false (or 0). It could probably be rewritten to use each() but I couldn't work it out.
<?php
function array_move_element($array, $value, $direction = 'up') {
   
    $temp = array();
   
    if(end($array) == $value && $direction == 'down') {
        return $array;
    }
    if(reset($array) == $value && $direction == 'up') {
        return $array;
    }

    while ($array_value = current($array)) {
       
        $this_key = key($array);

        if ($array_value == $value) {
            if($direction == 'down') {
                $next_value = next($array);
                $temp[key($array)] = $next_value;
                $temp[$this_key] = $array_value;
            } else {
                $prev_value = prev($array);
                $prev_key = key($array);
                unset($temp[$prev_key]);
                $temp[$this_key] = $array_value;
                $temp[$prev_key] = $prev_value;
                next($array);
                next($array);
            }
            continue;
        } else {
            $temp[$this_key] = $array_value;
        }

        next($array);
    }
    return $temp;
   
}
?>

kroczu at interia dot pl (06-Jul-2006 02:53)

<?
//A little function to convert array to simle xml:

function array_xml($array, $num_prefix = "num_")
{
    if(!is_array($array)) // text
    {
        return $array;
    }
    else
    {
        foreach($array as $key=>$val) // subnode
        {
            $key = (is_numeric($key)? $num_prefix.$key : $key);
            $return.="<".$key.">".array_xml($val, $num_prefix)."</".$key.">";
        }
    }

    return $return;
}

//example:

$array[0][0]                    = 1;
$array[0]['test']               = "test";
$array['test1']['test2']        = "test";
$array['test'][0]               = "test";
$array['test'][1]['test_x']     = $array;

print_r($array);

print"<xml>";

print array_xml($array);

print"</xml>";

/*

print_r($array) previev:

Array
(
    [0] => Array
        (
            [0] => 1
            [test] => test
        )
    [test1] => Array
        (
            [test2] => test
        )
    [test] => Array
        (
            [0] => test
            [1] => Array
                (
                    [test_x] => Array
                        (
                            [0] => Array
                                (
                                    [0] => 1
                                    [test] => test
                                )
                            [test1] => Array
                                (
                                    [test2] => test
                                )
                            [test] => Array
                                (
                                    [0] => test
                                )
                        )
                )
        )
)

result xml in firefox preview:

-<xml>
    -     <num_0>
            <num_0>1</num_0>
            <test>test</test>
        </num_0>
    -    <test1>
            <test2>test</test2>
        </test1>
    -    <test>
            <num_0>test</num_0>
        -    <num_1>
            -    <test_x>
                -    <num_0>
                        <num_0>1</num_0>
                        <test>test</test>
                    </num_0>
                -    <test1>
                        <test2>test</test2>
                    </test1>
                -    <test>
                        <num_0>test</num_0>
                    </test>
                </test_x>
            </num_1>
        </test>
 </xml>

*/
?>

vinaur at gmail dot com (06-Jun-2006 09:36)

Regarding the array to string (parse_line) and string to array (parse_array) functions posted below by Kevin Law.

The functions will not work correctly if the array being parsed contains values that include commas and possibly parentheses.

To solve this problem I added urlencode and urldecode functions and the result looks like this:

<?php
function parse_line($array){
    $line = "";
    foreach($array AS $key => $value){
        if(is_array($value)){
            $value = "(". parse_line($value) . ")";
        }
        else
        {
            $value = urlencode($value);
        }
        $line = $line . "," . urlencode($key) . ":" . $value . "";           
    }
    $line = substr($line, 1);
    return $line;
}

function parse_array($line){
   $q_pos = strpos($line, ":");
   $name = urldecode(substr($line,0,$q_pos));
   $line = trim(substr($line,$q_pos+1));
   $open_backet_pos = strpos($line, "(");

   if($open_backet_pos===false || $open_backet_pos>0){
       $comma_pos = strpos($line, ",");
       if($comma_pos===false){
           $result[$name] = urldecode($line);
           $line = "";
       }else{
           $result[$name] = urldecode(substr($line,0,$comma_pos));
           $result = array_merge($result, parse_array(substr($line,$comma_pos+1)));
           $line = "";
       }
   }else if ($open_backet_pos==0){
       $line = substr($line,1);
       $num_backet = 1;
       $line_char_array = str_split($line);
       for($index = 0; count($line_char_array); $index++){
           if($line_char_array[$index] == '('){
               $num_backet++;
           }else if ($line_char_array[$index] == ')'){
               $num_backet--;
           }
           if($num_backet == 0){
               break;
           }
       }
       $sub_line = substr($line,0,$index);
       $result[$name] = parse_array($sub_line);
       $line = substr($line,$index+2);
   }
   if(strlen($line)!=0){
       $result = array_merge($result, parse_array($line));
   }

   return $result;
}
?>

elkabong at samsalisbury dot co dot uk (24-Mar-2006 10:31)

Hello all! I've just been working on a system to automatically manage virtualhosts on an Apache box and I needed to duplicate some multidimensional arrays containing references to other multidimensional array some of which also contained references. These big arrays are defaults which need to be overwritten on a per-virtualhost basis, so copying references into the virtualhost arrays was not an option (as the defults would get corrupted).

After hours of banging me head on the wall, this is what I've come up with:
<?PHP # Tested on PHP Version 5.0.4
# Recursively set $copy[$x] to the actual values of $array[$x]
function array_deep_copy (&$array, &$copy) {
    if(!is_array($copy)) $copy = array();
    foreach($array as $k => $v) {
        if(is_array($v)) {
            array_deep_copy($v,$copy[$k]);
        } else {
            $copy[$k] = $v;
        }
    }
}
# To call it do this:
$my_lovely_reference_free_array = array();
array_deep_copy($my_array_full_of_references, $my_lovely_reference_free_array);
# Now you can modify all of $my_lovely_reference_free_array without
# worrying about $my_array_full_of_references!
?>
NOTE: Don't use this on self-referencing arrays! I haven't tried it yet but I'm guessing an infinate loop will occur...

I hope someone finds this useful, I'm only a beginner so if there's any fatal flaws or improvements please let me know!

alessandronunes at gmail dot com (18-Mar-2006 10:06)

The Ninmja sugestion plus multidiomensional array search (recursive):

function cleanArray($array) {
   foreach ($array as $index => $value) {
        if(is_array($array[$index])) $array[$index] = cleanArray($array[$index]);
        if (empty($value)) unset($array[$index]);
   }
   return $array;
}

Atomo64 (04-Jan-2006 01:14)

Here's a simple way to convert an array to a string and vice-versa.
Note that it does NOT support string keys,
for more information take a look at what it does:

<?php
class OptionAsArray
{
    function make_the_arr($value)
    {
        $newValue=array();
        $vals=explode('&',$value);
        foreach($vals as $v)
        {
            if($v{0}=='@')
            $newValue[]=$this->make_the_arr(
            urldecode(substr($v,1)));
            else
            $newValue[]=urldecode($v);
        }
        if(empty($newValue))
        return false;
        else
        return $newValue;
    }
    function make_the_value($arr)
    {
        $newValue=array();
        foreach($arr as $value)
        {
            if(is_array($value))
            $newValue[]='@'.urlencode(
            implode('&',$this->make_the_value($value)));
            else
            $newValue[]=urlencode($value);
        }
        if(empty($newValue))
        return false;
        else
        return $newValue;
    }
}
?>

jonathan at sharpmedia dot net (05-Dec-2005 02:37)

/**
 * Flattens a multimentional array.
 *
 * Takes a multi-dimentional array as input and returns a flattened
 * array as output. Implemented using a non-recursive algorithm.
 * Example:
 * <code>
 * $in = array('John', 'Jim', array('Jane', 'Jasmine'), 'Jake');
 * $out = array_flatten($in);
 * // $out = array('John', 'Jim', 'Jane', 'Jasmine', 'Jake');
 * </code>
 *
 * @author        Jonathan Sharp <jonathan@sharpmedia.net>
 * @var            array
 * @returns        array
 */
function array_flatten($array)
{
    while (($v = array_shift($array)) !== null) {
        if (is_array($v)) {
            $array = array_merge($v, $array);
        } else {
            $tmp[] = $v;
        }
    }
   
    return $tmp;
}

stalker at ruun dot de (20-Nov-2005 09:15)

I had some problems while selecting sub-arrays from multi-dimensional arrays (like the SQL-WHERE clause), so i wrote the following function:

<?php
function selectMultiArray($__multiarray,$__key,$__value) {
  foreach($__multiarray as $multipart) {
    if($multipart[$__key] == $__value) {
      $__return[] = $multipart;
    }
  }
  if(empty($__return)) {
    return FALSE;
  }
  return $__return;
}
?>

hope someones finding this helpful. If you have better was for getting to this, please answer.

greets,
St4Lk3R

msajko at gmail dot com (19-Oct-2005 09:25)

array_to_string and sister function string_to_array with multi dimensional array support.

// Converts an array to a string that is safe to pass via a URL
function array_to_string($array) {
   $retval = '';
   $null_value = "^^^";
   foreach ($array as $index => $val) {
       if(gettype($val)=='array') $value='^^array^'.array_to_string($val);    else $value=$val;
       if (!$value)
           $value = $null_value;
       $retval .= urlencode(base64_encode($index)) . '|' . urlencode(base64_encode($value)) . '||';
   }
   return urlencode(substr($retval, 0, -2));
}
 
// Converts a string created by array_to_string() back into an array.
function string_to_array($string) {
   $retval = array();
   $string = urldecode($string);
   $tmp_array = explode('||', $string);
   $null_value = urlencode(base64_encode("^^^"));
   foreach ($tmp_array as $tmp_val) {
       list($index, $value) = explode('|', $tmp_val);
       $decoded_index = base64_decode(urldecode($index));
       if($value != $null_value){
           $val= base64_decode(urldecode($value));
           if(substr($val,0,8)=='^^array^') $val=string_to_array(substr($val,8));
           $retval[$decoded_index]=$val;
          }
       else
           $retval[$decoded_index] = NULL;
   }
   return $retval;
}

phpnet_spam at erif dot org (18-Oct-2005 02:36)

Thought this might save someone a few hours. :)  Feedback welcome, of course!  Public domain, yadda yadda.

function assocSort(&$array,$key) {
    if (!is_array($array) || count($array) == 0) return true;
    $assocSortCompare  = '$a = $a["'.$key.'"]; $b = $b["'.$key.'"];';

    if (is_numeric($array[0][$key])) {
      $assocSortCompare.= ' return ($a == $b) ? 0 : (($a < $b) ? -1 : 1);';
    } else {
      $assocSortCompare.= ' return strcmp($a,$b);';
    }

    $assocSortCompare = create_function('$a,$b',$assocSortCompare);
    return usort($array,$assocSortCompare);
}

designatevoid at gmail dot com (14-Oct-2005 02:40)

Here's an improvement to the array_to_string and string_to_array functions posted by daenders AT yahoo DOT com above.

They now handle NULL values correctly.

<?php

// Converts an array to a string that is safe to pass via a URL
function array_to_string($array) {
    $retval = '';
    $null_value = "^^^";
    foreach ($array as $index => $value) {
        if (!$value)
            $value = $null_value;
        $retval .= urlencode(base64_encode($index)) . '|' . urlencode(base64_encode($value)) . '||';
    }
    return urlencode(substr($retval, 0, -2));
}
 
// Converts a string created by array_to_string() back into an array.
function string_to_array($string) {
    $retval = array();
    $string = urldecode($string);
    $tmp_array = explode('||', $string);
    $null_value = urlencode(base64_encode("^^^"));
    foreach ($tmp_array as $tmp_val) {
        list($index, $value) = explode('|', $tmp_val);
        $decoded_index = base64_decode(urldecode($index));
        if($value != $null_value)
            $retval[$decoded_index] = base64_decode(urldecode($value));
        else
            $retval[$decoded_index] = NULL;
    }
    return $retval;
}

?>

aidan at php dot net (09-Oct-2005 09:32)

To convert an array to a HTML table, see:
http://aidanlister.com/repos/v/function.array2table.php

PEAR also provides a simular package with many more features,
http://pear.php.net/package/Var_Dump

za at lombardiacom dot it (27-Sep-2005 04:01)

<?php
    // Swap 2 elements in array preserving keys.
    function array_swap(&$array,$key1,$key2) {
        $v1=$array[$key1];
        $v2=$array[$key2];
        $out=array();
        foreach($array as $i=>$v) {
            if($i==$key1) {
                $i=$key2;
                $v=$v2;
            } else if($i==$key2) {
                $i=$key1;
                $v=$v1;
            }
            $out[$i]=$v;
        }
        return $out;
    }

    // Move an element inside an array preserving keys.
    function array_move(&$array,$key,$position) {
        $from=array_search($key,array_keys($array));
        $to=$from+$position;   
        $tot=count($array);
        if($position>0) $to++;
        if($to<0) $to=0;
        else if($to>=$tot) $to=$tot-1;
        $n=0;
        $out=array();
        foreach($array as $i=>$v) {
            if($n==$to) $out[$key]=$array[$key];
            if($n++==$from) continue;
            $out[$i]=$v;
        }       
        return $out;
    }
?>

Domenic Denicola (15-Aug-2005 07:49)

Another JavaScript conversion, this time to objects instead of arrays. They can be accessed the same way, but are declared much shorter, so it saves some download time for your users:

<?
function PhpArrayToJsObject($array, $objName)
{
    return 'var ' . $objName . ' = ' . PhpArrayToJsObject_Recurse($array) . ";\n";
}

function PhpArrayToJsObject_Recurse($array)
{
    // Base case of recursion: when the passed value is not a PHP array, just output it (in quotes).
    if(! is_array($array) )
    {
        // Handle null specially: otherwise it becomes "".
        if ($array === null)
        {
            return 'null';
        }
       
        return '"' . $array . '"';
    }
   
    // Open this JS object.
    $retVal = "{";

    // Output all key/value pairs as "$key" : $value
    // * Output a JS object (using recursion), if $value is a PHP array.
    // * Output the value in quotes, if $value is not an array (see above).
    $first = true;
    foreach($array as $key => $value)
    {
        // Add a comma before all but the first pair.
        if (! $first )
        {
            $retVal .= ', ';
        }
        $first = false;
       
        // Quote $key if it's a string.
        if (is_string($key) )
        {
            $key = '"' . $key . '"';
        }
       
        $retVal .= $key . ' : ' . PhpArrayToJsObject_Recurse($value);
    }

    // Close and return the JS object.
    return $retVal . "}";
}
?>

Difference from previous function: null values are no longer "" in the object, they are JavaScript null.

So for example:

<?
$theArray = array("A" => array("a", "b", "c" => array("x")), "B" => "y");
echo PhpArrayToJsObject($theArray, "myArray");
?>

Gives:

var myArray = {"A" : {0 : "a", 1 : "b", "c" : {0 : "x"}}, "B" : "y"};

You can still access them just like arrays, with myArray["A"][0] or myArray["A"]["c"][0] or whatever. Just shrinks your pages.

dieter peeters (11-Aug-2005 12:35)

in response to: Domenic Denicola

I reworked your function a bit and thought i just as well could post it.

Below is the cleaner version, just cut and paste ;) The third parameter is of little use to the coder, unless javascript declaration of variables changes at some point in the future - who knows.

Only minor point is the added parameter which probably gets copied every recursive call with an empty value, though i don't know the exact ways how php handles recursion internally. Most of the time php is pretty smart when optimizing code and an empty string shouldn't take much memory anyway :)

<?php
function phpArrayToJsArray($name,$array,$prePend='var ')
{
    if (is_array($array)) { // Array recursion
        $result = $name.' = new Array();'."\n";
        foreach ($array as $key => $value) {
           $result .= phpArrayToJsArray($name.'["'.$key.'"]',$value,'');
        }
    } else {  // Base case of recursion
        $result = $name.' = "'.$array.'";'."\n";
    }
    return $prePend.$result;
}
?>

michael at imreo com (21-Jul-2005 01:20)

Reply to array_cartesian_product of skopek at mediatac dot com, 13-Oct-2004 12:44:

Your function does not work in my configuration (WinXP, apache 2.0, php 4.3.11).
This part of code:
...
} else { //if next returns false, then reset and go on with previuos array...
  reset($arrays[$j]);
}
...
cause infinite loop.
Replacing to
...
} elseif (isset($arrays[$j])) {
  reset($arrays[$j]);
}
...
works good.

My complete working function (additionaly strings as keys are allowed):
<?php
function array_cartesian_product($arrays)
{
    $result = array();
    $arrays = array_values($arrays);
    $sizeIn = sizeof($arrays);
    $size = $sizeIn > 0 ? 1 : 0;
    foreach ($arrays as $array)
        $size = $size * sizeof($array);
    for ($i = 0; $i < $size; $i ++)
    {
        $result[$i] = array();
        for ($j = 0; $j < $sizeIn; $j ++)
            array_push($result[$i], current($arrays[$j]));
        for ($j = ($sizeIn -1); $j >= 0; $j --)
        {
            if (next($arrays[$j]))
                break;
            elseif (isset ($arrays[$j]))
                reset($arrays[$j]);
        }
    }
    return $result;
}
?>

daenders AT yahoo DOT com (08-Jul-2005 09:49)

Several people here have posted functions for converting arrays to strings, but nobody posted a sister function that would convert it back.  Also, their data is not URL safe.  These functions are URL safe, hide the data by MIME encoding it, and are much shorter.  Enjoy.  :-)

<?php

// Converts an array to a string that is safe to pass via a URL
function array_to_string($array) {
    $retval = '';
    foreach ($array as $index => $value) {
        $retval .= urlencode(base64_encode($index)) . '|' . urlencode(base64_encode($value)) . '||';
    }
    return urlencode(substr($retval, 0, -2));
}
   
// Converts a string created by array_to_string() back into an array.
function string_to_array($string) {
    $retval = array();
    $string = urldecode($string);
    $tmp_array = explode('||', $string);
    foreach ($tmp_array as $tmp_val) {
        list($index, $value) = explode('|', $tmp_val);
        $retval[base64_decode(urldecode($index))] = base64_decode(urldecode($value));
    }  
    return $retval;
}

// Example:
$array1 = array('index1' => 'val1', 'index2' => 'val2', 'index3' => 'val3');
echo '<pre>'; print_r($array1); echo '</pre>';
$string = array_to_string($array1);
echo '$string: '.$string.'<br />';
$array2 = string_to_array($string);
echo '<pre>'; print_r($array2); echo '</pre>';

?>

m227(a)poczta.onet.pl (20-Jan-2005 04:18)

How to count dimensions in multi-array? (corrected)

previous version didn't work when called more than one time.
($dimcount was preserved from previous call)

This is the way I corrected this:

function countdim($array)
  {
    if (is_array(reset($array)))  
      $return = countdim(reset($array)) + 1;
    else
      $return = 1;
 
    return $return;
  }

This function will return int number of array dimensions.