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join> <htmlspecialchars
Last updated: Fri, 04 Jul 2008

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implode

(PHP 4, PHP 5)

implode — Une elementos de una matriz mediante una cadena

Descripción

string implode ( string $elemento_union , array $trozos )

Devuelve una cadena que contiene una representación de todos los elementos de la matriz en el mismo orden, pero con la cadena elemento_union en medio de los mismos.

Example #1 Ejemplo de implode()

<?php

$array = array('apellido', 'email', 'telefono');
$separado_por_comas = implode(",", $array);

echo $separado_por_comas; // apellido,email,telefono

?>

Note: La función implode() puede, por razones históricas, acceptar sus parámetros en cualquier orden. Sin embargo, para mantener la consistencia con la función explode(), se recomienda emplear los parámetros en el orden indicado.

Note: Desde la versión de PHP 4.3.0, el parámetro elemento_union es opcional y su valor por defecto es una cadena vacía (''). De todas formas, para mantener la compatibilidad con versiones anteriores, se recomienda indicar siempre los 2 parámetros definidos.

Note: Esta función es segura binariamente.

Vea también explode() y split().



join> <htmlspecialchars
Last updated: Fri, 04 Jul 2008
 
add a note add a note User Contributed Notes
implode
mr dot bloar at gmail dot com
27-May-2008 07:12
A usefull version of implode() when you need to surround values, for example when you are working with nodes (HTML, XML)

function myImplode($before, $after, $glue, $array){
    $nbItem = count($array);
    $i = 1;
    foreach($array as $item){
        if($i < $nbItem){
            $output .= "$before$item$after$glue";
        }else $output .= "$before$item$after";
        $i++;
    }
    return $output;
}

$an_array = array('value1','value2');
print myImplode("<a href=\"#\">","</a>"," > ", $an_array);

output : <a href="#">value1</a> > <a href="#">value2</a>
ielastic at yandex dot ru
13-May-2008 02:51
function WriteCsv($fileName, $delimiter = '|', $records)
{

  $result = array();
  foreach($records as $key => $value)
    $results[] = implode($delimiter, $value);  //bad arguments
  $fp = fopen($fileName, 'w');
  foreach ($results as $result)
    fputcsv($fp, split("|", $result));
  fclose($fp);
}
wesleys at opperschaap dot net
01-Apr-2008 05:36
I'm new to PHP, coming from Perl and I already had a problem once when I wanted to join some strings. In perl you can use join to join a list (which can be an array and/or a list of strings and/or hashes), where PHP does this only with arrays. That annoyed me.
I could not find any code which did this, so I created my own join, based on Perl's join function. It is called p_join().

<?php

/* is_assoc_array and is_sequential_array are STOLEN from:
 * http://nl3.php.net/manual/en/function.is-array.php#73505 */
function is_assoc_array($var) {
        return (array_merge($var) !== $var || !is_numeric(implode(array_keys($var))));
}

function is_sequential_array($var) {
        return (array_merge($var) === $var && is_numeric(implode(array_keys($var))));
}

function _p_join_assoc($sep, $hash) {
        $result = "";
        foreach ($hash as $k => $v) {
                $result .= $sep . $k .  $sep . $v ;
        }
        return $result;
}

function _p_join_array($sep, $array) {
        # Turn off notices and return to the old loglevel once we're done.
        # This is because we stringify an array in some cases..
        $old_error_reporting = error_reporting(E_ALL ^ E_NOTICE);
        $result = join($sep, $array);
        error_reporting($old_error_reporting);
        return $result;
}

function p_join() {

        $args = func_get_args();

        if (count($args) > 1) {
                $result     = "";
                $sep = array_shift($args);

                foreach ($args as $val) {
                        if (is_array($val)) {
                                if (is_assoc_array($val)) {
                                        $result .= _p_join_assoc($sep, $val);
                                } else {
                                        $result .= $sep  . _p_join_array($sep, $val);
                                }
                                continue;
                        }
                        $result .= $sep . $val;
                }
                # $result will always start with a $sep, so remove it..
                return substr_replace($result, "" ,0, strlen($sep));
        }

        trigger_error(sprintf("%s requires at least 2 parameters",
          __FUNCTION__), E_USER_WARNING);
        return null;
}

/* And some example code */

print p_join(",", "string", array("Key" => "Value", "Key 2" => "Value 2"),
  array("Hello", array("in", "hello", "world"), "array"), "string 2") . "\n";

/* Watch out, prints de indices when it you supply a mixed array */
print p_join(",", array(1,2,"Green" => "Apple" , array(1,2))) . "\n";

print "Warning.. ";
print p_join(",");
?>
Anonymous
18-Feb-2008 03:41
So I looked through all the problem solutions  posted here, and combined them into one nice recursive function.

<?php

function implode_md( $glue, $array, $key = NULL, $list = NULL )
{
    if( !is_array( $array ) )
        return $array;
    if( !sizeof( $array ) )
        return "";
    if( !is_null( $key ) )
    {
        if( strpos( $key, "." ) )
        {
            $keys = array_reverse( explode( ".", $key ) );
            $currentKey = array_pop( $keys );
            if( sizeof( $keys ) ) $keys = implode( ".", $keys );
            else $keys = implode( "", $keys );
        }
        else
        {
            $currentKey = $key;
            $keys = NULL;
        }
        if( array_key_exists( $currentKey, $array ) )
            return implode_md( $glue, $array[$currentKey], $keys, $list );
        else
            return "";
    }
    if( !empty( $list ) )
    {
        $last = array_pop( $array );
        if( count( $array ) )
            return implode_md( $glue, $array, $key ) . " $list $last";
        else
            return $last;
    }
    $ret = array();
    for( $i = 0; $i < sizeof( $array ); $i++ )
        if( is_array( $array[$i] ) ) $ret[] = implode_md( $glue, $array[$i], $key, $list );
        else $ret[] = $array[$i];
    return implode( $glue, $ret );
}

?>
jimbob
12-Jan-2008 08:00
My take on a simple english list function - it's similar to what's already here, but calls count less

function x_implode_eng_list($array, $glue=', ', $final=' and '){
    //takes an array and outputs an English style list
    //perform the count once
    $count = count($array);
    //make sure it's an array and has content
    if((!is_array($array)) || ($count == 0)) {
        return '';
    } else {
        //pop off the end regardless of length
        $end = array_pop($array);
        //if there's more than one, implode the remainder using glue and append $end
        if($count>1){
            return implode($glue, $array) . $final . $end;
        } else {
            //only one value, return the popped end element
            return $end;
        }
    }
}
$names[] = 'bob';
$names[] = 'john';
$names[] = 'lucy';
echo x_implode_eng_list($names); //will output bob, john and lucy

echo x_implode_eng_list($names, ', ', ' or '); //will output bob, john or lucy
datacompboy at call2ru dot com
09-Nov-2007 11:50
suppose we have array $content with total size of 10Mb of text.

then,
  $content = join($content);
will run about 23 sec (on my machine -- athlon xp 2600+, 1.5 Gb ram)

and
  file_put_contents("tempfile", $content);
  $content = file_get_contents("tempfile");
will run for 0.12 sec (same machine).

so, think carefully about speed.
1413 at blargh dot com
10-Oct-2007 03:42
Below is the function for making an English-style list from an array, seems to be simpler than some of the other examples I've seen.

<?php
function ImplodeProper($arr, $lastConnector = 'and')
{
  if( !is_array($arr) or count($arr) == 0) return '';
  $last = array_pop($arr);
  if(count($arr))
    return implode(', ',$arr).", $lastConnector $last";
  else
    return $last; 
}
?>

Examples:
<?
   print ImplodeProper(array()).'<br>';
   print ImplodeProper(array('foo')).'<br>';
   print ImplodeProper(array('foo','bar')).'<br>';
   print ImplodeProper(array('for','bar','bleh')).'<br>';
?>

Yields:

foo
foo, and bar
for, bar, and bleh
sinatosk at gmail dot com
07-Oct-2007 05:42
This code implodes same as the PHP built in except it allows you to do multi dimension arrays ( similar to a function below but works dynamic :p.

<?php

function implode_md($glue, $array, $array_path='')
{
    if ( !empty($array_path) )
    {
        $array_path = explode('.', $array_path);
       
        if ( ( $array_path_sizeof = sizeof($array_path) ) < 1 )
        {
            return implode($glue, $array);
        }
    }
    else
    {
        return implode($glue, $array);
    }
   
    $str = '';
   
    $array_sizeof = sizeof($array) - 1;
   
    for ( $i = 0; $i < $array_sizeof; $i++ )
    {
        $value = $array[ $i ];
       
        for ( $j = 0; $j < $array_path_sizeof; $j++ )
        {
            $value =& $value[ $array_path[ $j ] ];
        }
       
        $str .= $value . $glue;
    }
   
    $value = $array[ $array_sizeof ];
   
    for ( $j = 0; $j < $array_path_sizeof; $j++ )
    {
        $value =& $value[ $array_path[ $j ] ];
    }
   
    $str .= $value;
   
    return $str;
}

?>

And heres an example on how to use this

<?php

$arr = array();
$arr[]['data']['id'] = 'a';
$arr[]['data']['id'] = 'b';
$arr[]['data']['id'] = 'c';
$arr[]['data']['id'] = 'd';
$arr[]['data']['id'] = 'e';
$arr[]['data']['id'] = 'f';
$arr[]['data']['id'] = 'g';

echo implode_md(',', $arr, 'data.id');

?>

The output of this code should be

'a,b,c,d,e,f,g'

When you want to work with more dimensions... say for example you have an array that is like this

<?php

$arr=array();
$arr[0]['game']['pc']['fps']['idsoftware'] = 'Quake';
$arr[1]['game']['pc']['fps']['idsoftware'] = 'Quake II';
$arr[2]['game']['pc']['fps']['idsoftware'] = 'Quake III Arena';

?>

on the third parameter... as a string you simply type in

<?php

echo implode_md(', ', $arr, 'game.pc.fps.idsoftware');

?>

and the output should be

'Quake, Quake II, Quake III Arena'

Enjoy ;)
thomas at tgohome dot com
09-Jul-2007 01:05
This is my quick function to create a list, English style, but will accept any glue, so you could use 'or', or even 'or though, it could be', etcetera. It should also support PHP 4, although I haven't tested it; it doesn't use the PHP 5 negative substr() trick.

<?php

/**
 * Quick script to join items in an array, English
 * style; using the "one, two and three" style.
 *
 * Copyright 2007 Thomas O. Feel free to redistribute
 * so long as this copyright remains.
 */

function implode_ea($glue_punct, $glue_word, $array) {
    // Implode the entire array
    $result = implode($glue_punct, $array);

    // Check the length of the array
    if(count($array) > 1) {
        // Calculate the amount needed to trim
        $trimamount = strlen($array[count($array) - 1]) + strlen($glue_punct);

        // Trim the imploded string
        $result = substr($result, 0, strlen($result) - $trimamount); // PHP 4 compatible
        $result = "$result $glue_word " . $array[count($array) - 1];

        // Return the result
        return $result;
    } else {
        // In this case, the array cannot be splitted by a
        // word or punctuation, because it is too small.
        return $result;
    }
}

echo implode_ea(", ", "and", array("one", "two", "three"));
?>

(implode_ea stands for 'Implode, English And style')

Hope this helps,
Tom
peter dot goodman at gmail dot com
04-Jul-2007 10:36
I came up with this nifty function to implode an Iterator or class that implements IteratorAggregate:

function implode_iterator($sep = '', $it) {
    $a = array();
   
    if(!$it instanceof Traversable) {
        throw new UnexpectedValueException('$it must implement Traversable.');
    }
   
    if($it instanceof IteratorAggregate) {
        $a = iterator_to_array($it, FALSE);
    } else if($it instanceof Iterator) {
        foreach($it as $val) {
            $a[] = $val;
        }
    }
   
    return implode($sep, $a);
}
Dennis Day
02-Jul-2007 02:39
I have resolved an issue in SquirrelMail.  The problem seemed to be with the implode command.  Apparently you do not want to use this function with a large array as SquirellMail attempted to do.  This only was an issue with some of the email attachments larger that 2MB.

In /src/move_messages.php, replace the line line that says

$body = implode('', $body_a);

With :

// Dennis Day's custom code
                $body = "";
                foreach($body_a as $body_a_key=>$body_a_value){
                                $body .= $body_a_value;
                }
// End Dennis Day's custom code

// Original Bad Code
//              $body = implode('', $body_a);
TheMadBomberWhatBombsAtMidnight
14-Jun-2007 08:46
in response to Brian, building a POST/GET string from an assoc array is easily done with the builtin http_build_query...as the example from its doc page shows:

<?php
$data = array('foo'=>'bar',
              'baz'=>'boom',
              'cow'=>'milk',
              'php'=>'hypertext processor');

echo http_build_query($data); // foo=bar&baz=boom&cow=milk&php=hypertext+processor
?>

of course, the builtin function also urlencodes the string it returns, which Brian's function did not.
darwinkid at gmail dot com
20-Mar-2007 01:09
this is a little function i made to implode an array based on key. its main purpose is to implode elements within
a multi-dimensional array. its slightly different than some of the other examples because it makes use of some
PHP SPL features. if your not using PHP5, this definitely won't work for you.

let me know what you think!

<?php
function implode_by_key($glue, $keyname, $pieces)
{

    // create a new recursive iterator to get array items
    $it = new RecursiveIteratorIterator(new RecursiveArrayIterator($pieces));

    $arr = array();

    foreach($it AS $element) {

        if ($it->key() == $keyname) {

            $arr[] = $it->current();

        }

    }

    return implode($glue, $arr);

}

// here is an example

$array = array(
            array('somekey' => 'somevalue'),
            array(
                array('key2' => 'anoter value'),
                array('key2' => 'another sub value'),
                array(
                    array('key3' => 'asdlkfs jdafajdshf aoufiahsdlkfjsadf'),
                    array(
                        array('key4' => 'this is key 4 - 1'),
                        array('key4' => 'this is key 4 - 2'),
                        array('key4' => 'this is key 4 - 3'),
                        array(
                            array('key5' => 'asdfkajsdflkasjdfklajshfkljasfhasdfasdf'),
                            array('key5' => 'asdfkajsdflkasjdfklajshfkljasfhasdfasdf'),
                        )                                   
                    )
                )

            )
        );

echo implode_by_key('<br/>', 'key4', $array);
?>

This outputs:

this is key 4 - 1
this is key 4 - 2
this is key 4 - 3
Hayley
19-Mar-2007 03:52
And adding one more case to drewish at katherinehouse dot com's code to deal with the two-element case "a and b":

<?php
case 2:
    return reset($array).' and '.end($array);
?>

Of course, then one can start considering Oxford rules again, and maybe testing that the argument really is an array....

<?php
function english_list($array, $useOxfordComma=false)
{
    if(!is_array($array))
        return '';
    switch(count($array))
    {
    case 0:
        return '';
    case 1:
        // This may not be a normal numerically-indexed array.
        return reset($array);
    case 2:
        return reset($array).' and '.end($array);
    default:
        $last = array_pop($array);
        return implode(', ', $array).($useOxfordComma?',':'').' and '.$last;
    }
}
?>
ahigerd at stratitec dot com
04-Jan-2007 06:43
Note that PHP uses copy-on-write so passing parameters (even array parameters) by reference gains you no performance benefit, and in fact in some cases can HURT performance.

For example:

php > $array = array('a','s','d','f');
php > $start = microtime(true); for($i=0; $i<1000000; $i++) byref($array); echo microtime(true)-$start;
2.40807890892
php > $start = microtime(true); for($i=0; $i<1000000; $i++) byval($array); echo microtime(true)-$start;
1.40822386742
bishop
23-Nov-2006 06:33
The english_list() implementation of davidpk212 at gmail dot com, Andy Morris, and tshort at cisco dot com does not handle the case of a two-element array with Oxford comma.  Example:

<?php
english_list(array ('a', 'b'), true) // == 'a, and b'
// should be 'a and b'
?>

Here's another implementation that addresses this issue, uses pass-by-reference without modifying the array, and illustrates yet another approach to solving the problem:

<?php
function english_list(&$array, $useOxfordComma = false) {
    $count = (is_array($array) ? count($array) : 0);
    if (3 <= $count) {
        $last = end($array);
        $list = prev($array) . ($useOxfordComma ? ', and ' : ' and ') . $last;
        while ($v = prev($array)) {
            $list = $v . ', ' . $list;
        }   
    } else if (2 == $count) {
        $last = end($array);
        $list = prev($array) . ' and ' . $last;
    } else if (1 == $count) {
        $list = end($array);
    } else {
        return '';
    }       
            
    reset($array);
    return $list;
}           
?>

Run times for this version are comparable to the run times for heir earlier posted versions.
richard at happymango dot me dot uk
23-Nov-2006 04:43
This is a simple function that is the same as implode except it allows you to specify two glue parameters instead of one so an imploded array would output "this, this, this and this" rather than "this, this, this, this, this".

This is useful if you want to implode arrays into a string to echo as part of a sentence.

It uses the second glue between the last two items and the first glue between all others. It will use the second glue if there are only two items to implode so it would output "this and this".

<?php

function implode2($glue1, $glue2, $array)
{
    return ((sizeof($array) > 2)? implode($glue1, array_slice($array, 0, -2)).$glue1 : "").implode($glue2, array_slice($array, -2));
}

//example below

$array = array("Monday", "Tuesday");
echo "1: ".implode2(', ', ' and ', $array)."<br />";

$array = array("Mon", "Tue", "Wed", "Thu", "Fri");
echo "2: ".implode2(', ', ' &amp; ', $array)."<br />";

$array = array( 1, 2, 3, 4, 10);
echo "3: ".implode2(' + ', ' = ', $array)."<br />";

?>

This outputs

1: Monday and Tuesday
2: Mon, Tue, Wed, Thu & Fri
3: 1 + 2 + 3 + 4 = 10
Demonisch
05-Oct-2006 02:11
Very simple function for imploding a certain column in a 2D array. Useful if you have fetched records from a database in an associative array and want to store all the values in a certain column as a string, for use with JavaScript or passing values from page to page.

$sep = the separator, such as " ", "," or "&amp;"
$array = the 2D associative array
$key = the column key, such as "id"

Feel free to add error protection

function implodeArray2D ($sep, $array, $key)
{
   
    $num = count($array);
    $str = "";
   
    for ($i = 0; $i < $num; $i++)
    {
       
        if ($i)
        {
            $str .= $sep;
        }
       
        $str .= $array[$i][$key];
       
    }
   
    return $str;
   
}
triptripon at gmail dot com
05-Sep-2006 02:18
Here's my 2 matching (implode|explode)_with_key functions.
Notice, the inglue, outglue cannot appear within the keys\values.

function implode_with_key($assoc, $inglue = '>', $outglue = ',')
    {
        $return = '';
        foreach ($assoc as $tk => $tv)
        {
            $return .= $outglue . $tk . $inglue . $tv;
        }
        return substr($return,strlen($outglue));
    }
   
   
    function explode_with_key($str, $inglue = ">", $outglue = ',')
    {
        $hash = array();
        foreach (explode($outglue, $str) as $pair)
        {           
            $k2v = explode($inglue, $pair);           
            $hash[$k2v[0]] = $k2v[1];           
        }
        return $hash;
    }

-- Tomer Levinboim
worldwideweb dot C-Kling dot de
12-Aug-2006 12:15
A Script for imploding a multideimensional Array. You give an array of separators in the first argument, and a (multidimensional) array in the second. The script will return the imploded array.

<?php
function multimplode($spacer,$array)
    {
    if (!is_array($array))
        {
        return($array);
        }   
    if (empty($spacer))
        {
        return(multimplode(array(""),$array));
        }
    else
        {
        $trenn=array_shift($spacer);
        while (list($key,$val) = each($array))
            {
            if (is_array($val))
                {
                $array[$key]=multimplode($spacer,$val);
                }
            }
        $array=implode($trenn,$array);
        return($array);
        }
    }
?>
adnan at barakatdesigns dot net
23-May-2006 09:17
An easier way of achieving the same result as implode_with_keys() - and quicker execution time:

<?
/* NOTE: $glue is not used if $is_query is true */
function implode_with_keys($array, $glue, $is_query = false) {
    if($is_query == true) {
        return str_replace(array('[', ']', '&'), array('%5B', '%5D', '&amp;'), http_build_query($array));

    } else {
        return urldecode(str_replace("&", $glue, http_build_query($array)));

    }

}

echo implode_with_keys(array('a[1]' => 'some text', 'a[2]' => 'even more text'), false, true);
/* Will output 'a%5B1%5D=some+text&amp;a%5B2%5D=even+more+text' */
/* This won't break html validation */

echo implode_with_keys(array('a[1]' => 'foo bar', 'b' => 'more text'), '|');
/* Will output 'a[1]=foo bar|b=more text' */
?>
dabduster at gmail dot com
03-Jan-2006 08:39
an implementation of adrian at foeder dot de implode_with_keys function for input and update sql statement.

function implode_param($glue, $array, $valwrap='', $mode = 0)
   {
    /*   
    if mode = 0 output is key and values
    if mode = 1 output only keys
    if mode = 2 output only values
    */
   
    switch ($mode){
        case 1:
               foreach($array AS $key => $value) {
                   $ret[] = $valwrap.$key.$valwrap;
               }
        break;
       
        case 2:
               foreach($array AS $key => $value) {
                   $ret[] = $valwrap.$value.$valwrap;
               }
        break;

        default:
        case 0:
               foreach($array AS $key => $value) {
                   $ret[] = $key."=".$valwrap.$value.$valwrap;
               }
        break;
       
    }
       
       
    return implode($glue, $ret);
}
adrian at foeder dot de
31-Oct-2005 04:53
...and a mysql-update-statement-compatible implementation of implode_with_keys:

<?php
function implode_with_keys($glue, $array, $valwrap='')
    {
        foreach($array AS $key => $value) {
            $ret[] = $key."=".$valwrap.$value.$valwrap;
        }
        return implode($glue, $ret);
    }
?>

so implode_with_keys(", ", $array, "'") will output:

key1='value1', key2='value2'

and so on. Useful for UPDATE table SET key1='value1', key2='value2'
Peter Hopfgartner
27-Sep-2005 07:26
Correctly initializing all variables, this would become:

function implode_with_key($assoc, $inglue = '=', $outglue = '&'){
    $return = '';
    foreach ($assoc as $tk => $tv) {
        $return = ($return != '' ? $return . $outglue : '') .
            $tk . $inglue . $tv;
    }
    return $return;
}

Note, the return value is also well defined if $assoc is empty.

Regards
php at josh dot jeppsons dot org
09-Sep-2005 09:22
Another variation on implode_with_key:

<?php
  function implode_with_key($assoc, $inglue = '=', $outglue = '&')
    foreach ($assoc as $tk => $tv) {
      $return = (isset($return) ? $return . $outglue : '') . $tk . $inglue . $tv;
    }
    return $return;
  }
?>
pr10n at spymac dot com
29-Aug-2005 09:46
A little tweak on info at urbits dot com's suggestion just incase someone changes their value of $outglue:

<?php
function implode_with_key($assoc, $inglue = '=', $outglue = '&')
{
   $return = null;
   foreach ($assoc as $tk => $tv) $return .= $outglue.$tk.$inglue.$tv;
   return substr($return,strlen($outglue));
}
?>
info at urbits dot com
19-Aug-2005 06:06
I liked memandeemail's (27-Apr-2005) neat code for imploding an associative array. I have done a mod so that, by default, it returns a url query string.

<?php
function implode_with_key($assoc, $inglue = '=', $outglue = '&')
{
   $return = null;
   foreach ($assoc as $tk => $tv) $return .= $outglue.$tk.$inglue.$tv;
   return substr($return,1);
}
?>

Example:
<?php
$assoc_array = array("a" => "foo", "b" => "bar", "c" => "foobar");
echo (implode_with_key($assoc_array);
?>

ouput: a=foo&b=bar&c=foobar

usage: After altering the $HTTP_GET_VARS values, I pass $HTTP_GET_VARS to the function to easily build variation urls for links and header redirects.

note: This function doesn't encode the url string or check for empty variables.
cristianDOTzuddas [AT] gmailDOTcom
07-Jul-2005 12:22
...and another variation of "implode_assoc" function. Just added the boolean parameter $urlencoded; if TRUE returns the array value in URL encod format. If the parameter is not given it behaves like the original function.

<?
function implode_assoc($inner_glue, $outer_glue, $array, $skip_empty=false, $urlencoded=false) {
    $output = array();
    foreach($array as $key=>$item) {
        if (!$skip_empty || isset($item)) {
            if ($urlencoded)
                $output[] = $key.$inner_glue.urlencode($item);
            else
                $output[] = $key.$inner_glue.$item;
        }
    }
   
    return implode($outer_glue, $output);
}
?>
sam dot bledsoe at nosp at nn dot gmail dot com
31-May-2005 08:57
The function below recursively outputs an array in a format condusive to parsing it in php or another scripting language.  It does NOT output the name of the original array, for that see note 1.  It handles all the cases I could think of elegantly.  Comments and criticisms are welcome.

For an array constructed with:

$arr = array("foo" => array('bar' => array(0 => "value 0", 1 => "value 1")), "foo two" => array(0 => array("bar" => "value2")));

The line below:

echo implode_parseable("=", ";<br>$", $arr, "$", ";");

Will produce:

$foo["bar"][0]="value 0";
$foo["bar"][1]="value 1";
$foo_two[0]["bar"]="value2";

NOTES:
1)  If the leading identifier on a line is a number, the output will most likely be unusable since variable names cannot begin with numbers.  You can get around this by doing something like:
$arr = array('arr' => $arr);
This will output the array as it actually is (because the key is the same name as the array) instead of just its fields.
2)  Since spaces are not allowed in variable names, they are replaced in lines' leading identifiers by the $space_replace_char parameter, '_' by default.

Hopefully someone will find this useful, if so drop me a line.  Credit and thanks go out to the people who posted their code on this manual page, especially davidpk212 at gmail dot com and phpWalter at torres dot ws.

function implode_parseable($inner_glue = "=", $outer_glue = "\n", $array = null, $prefix = "", $suffix = "", $space_replace_char = '_', $skip_empty = false, $current_loc = "", $recursion_level = 0){
  return $prefix . implode_parseable_r($inner_glue, $outer_glue, $array, $space_replace_char, $skip_empty, $current_loc, $recursion_level) . $suffix;
}

function implode_parseable_r($inner_glue = "=", $outer_glue = "\n", $array = null, $space_replace_char = '_', $skip_empty = false, $current_loc = "", $recursion_level = 0)
{
  if(is_array($array)){
    $output = array();
    foreach( $array as $key => $item ){
      if ( is_array ($item) ){
       
        //don't quote numeric indicies
        if(is_string($key))
          $quoted_key = "\"" . $key . "\"";
        else
          $quoted_key = $key;

        // This is value is an array, go and do it again!
        $level = $recursion_level + 1;
        if($recursion_level == 0){
          // can't have spaces in a variable name!
          $current_loc .= str_replace(' ', $space_replace_char, $key);
          $output[] = implode_parseable_r ($inner_glue, $outer_glue, $item,  '_', $skip_empty, $current_loc, $level);
          //start the position tracker over after every run from level 0
          $current_loc = '';
        }else{
          $current_loc .= "[" . $quoted_key . "]";
          $output[] = implode_parseable_r ($inner_glue, $outer_glue, $item,  '_', $skip_empty, $current_loc, $level);
          //remove the last index from the position tracker string after using it
          $current_loc = ereg_replace('\[[^]]*\]$', '', $current_loc);
        }

      }
      else{
        //  don't quote or []ify the base variable name,
        //  but do for all else as appropriate
        if($recursion_level != 0){
            if(is_string($key))
              $key = "\"" . $key . "\"";
            $key = "[" . $key . "]";
        }
//        echo "<br>";
//        var_dump($item);
//        echo "<br>";

        $skip_this = false;
        if($skip_empty && (!isset($item) || $item == NULL || $item == '')) $skip_this = true;

        //quote the item (which is the value of the array index) if it is a string
        if(is_string($item)) $item = "\"" . $item . "\"";

        if(!$skip_this) $output[] = $current_loc . $key . $inner_glue . $item;
      }
    }
    return implode($outer_glue, $output);
  }else{
    return $array;
  }
}
Klába
31-May-2005 05:42
in case of value $item==0 but is set is necessary use function isset()

function implode_assoc($inner_glue,$outer_glue,$array,$skip_empty=false){
 $output=array();
 foreach($array as $key=>$item)
  if(!$skip_empty || isset($item)){$output[]=$key.$inner_glue.$item;}
 return implode($outer_glue,$output);
}
killroy at g m a i l dot c o m
16-May-2005 01:29
Here is another variation on Chris' function. I added a $skip_empty parameter. if it's set to TRUE the result string will not contain keys whose values are empty. Great for building query_strings. If the parameter is not given it behaves like the original function:

$a='1';
$b='';
$c='3';

INPUT: implode_assoc('=','&',array('a'=>$a,'b'=>$b,'c'=>$c),true);
OUTPUT: a=1&c=3

INPUT: implode_assoc('=','&',array('a'=>$a,'b'=>$b,'c'=>$c));
OUTPUT: a=1&b=&c=3

function implode_assoc($inner_glue,$outer_glue,$array,$skip_empty=false){
 $output=array();
 foreach($array as $key=>$item)
  if(!$skip_empty || $item){$output[]=$key.$inner_glue.$item;}
 return implode($outer_glue,$output);
}
tshort at cisco dot com
29-Apr-2005 07:20
Correction: I meant "passed by value", not "pass by reference". My mistake. Passing by reference would speed up any of these functions by avoiding the copy necessary for "by value.

Other solutions have problems with non-arrays as well. But it demonstrates that there are many ways to solve this problem. Adding checks for non-arrays and short arrays makes the solution less elegant, but safer. Other solutions should have included similar protections.

function english_list($array, $oxfordComma=0)
{
  if (!is_array($array)) return $array;
  if (count($array) <= 1) return join(", ", $array);
  $last = array_pop($array);
  return join(", ", $array) . ($oxfordComma ? "," : "") . " and " . $last;
}
Andy Morris
28-Apr-2005 05:27
It's always dangerous to give sweeping statements like "this will always work!". Your solution is much more elegant than mine, but perhaps it's a little too elegant for its own good! Try giving it an array with zero or one elements in it for example. You could say that folks shouldn't call it in that case, but you know folks... they like pushing the boundaries. :-)

Perhaps you meant to say that the array can be altered inside the function because it is passed "by value" rather than "by reference", or is that just a mixture of terminology from my C++ upbringing? Passing by reference would imply that you could alter the array inside the function and have that alter its value outside. Passing by value implies that any changes inside the function affect the local function copy only. In PHP, the latter is clearly the case, unless a variable is explicitly declared as global.

OK, that's my 2c.
tshort at cisco dot com
28-Apr-2005 01:54
/*
  english_list()
This one works with anything, since the array is passed by reference, modifying it in the function via pop has no effect on the array outside the function. But it can't be done on one line, because the array_pop() must occur before the join().
*/

function english_list($array, $oxfordComma=0)
{
  $last = array_pop($array);
  return join(", ", $array) . ($oxfordComma ? "," : "") . " and " . $last;
}
Andy Morris
28-Apr-2005 10:19
Similar to a previous note, but this works for any length array, plus also works for arrays with key strings instead of integer keys! I know it's not strictly an implode() example, but it concerns what you might be considering using implode() to help you to do achieve...

<?php
// Return array as a comma separated list; final two elements separated
// by 'and' with an optional "Oxford" comma preceding the 'and'.
function english_list($array, $oxfordComma=0)
{
  $optionalComma = ( $oxfordComma ) ? "," : "";
  $str = "";
  $size = count( $array );
  $i = 0;
  foreach ( $array as $item ) {
    $str .= $item;
    $i++;
    if ( $i < $size - 1) $str .= ", ";
    elseif ( $i == $size - 1) $str .= $optionalComma." and ";
  }
  return $str;
}

// test the comma separated list function
echo english_list( array(), 1 )."<br>";
echo english_list( array("foo"), 1 )."<br>";
echo english_list( array("foo", "bar"), 0 )."<br>";
echo english_list( array("a" => "foo", "b" => "bar", "c" => "foobar"), 1 )."<br>";
echo english_list( array("foo", "bar", "foobar", "barfoo"), 0 )."<br>";
?>
memandeemail at gmail dot com
27-Apr-2005 06:06
/**
     * Like implode but with keys
     *
     * @param string[optional] $glue
     * @param array $pieces
     * @param string[optional] $hifen
     * @return string
     */
    function implode_with_key($glue = null, $pieces, $hifen = ',') {
        $return = null;
        foreach ($pieces as $tk => $tv) $return .= $glue.$tk.$hifen.$tv;
        return substr($return,1);
    }
davidpk212 at gmail dot com
14-Apr-2005 08:36
I made this function to create an english-readable list from an array.

<?php
function english_list($array, $oxfordcomma=1) {
  $count = count($array)-1;
  $last = $array[$count];
  unset($array[$count]);
  $str = join(", ", $array);
  if ($oxfordcomma) {
    $str .= ",";
  }
  $str .= " and $last";
 
  return $str;
}
?>

The optional parameter "oxfordcomma" indicates whether or not to use the Oxford comma (a comma before the "and").

Example:

<?php
print english_list(array("foo", "bar", "foobar", "barfoo"));
?>
Would produce:

foo, bar, foobar, and barfoo
01-Apr-2005 06:07
Here is another varriation on the below code. This is useful if you are trying to store data as a string to be returned to an array later.  It allows unlimited nested arrays to be both stored and extracted, but does not print out as pretty.

function implode_assoc_r2($inner_glue = "=", $outer_glue = "\n", $recusion_level = 0, $array = null)
{
   $output = array();

   foreach( $array as $key => $item )
       if ( is_array ($item) )
       {
           // This is value is an array, go and do it again!
           $level = $recusion_level + 1;
           $output[] = $key . $inner_glue . $recusion_level . $inner_glue . implode_assoc_r ($inner_glue, $outer_glue, $level, $item, $keepOuterKey);
       }
       else
           $output[] = $key . $inner_glue . $recusion_level . $inner_glue . $item;

   return implode($outer_glue . $recusion_level . $outer_glue, $output);
}

function explode_assoc_r2($inner_glue = "=", $outer_glue = "\n", $recusion_level = 0, $string = null)
{
       $output=array();
       $array=explode($outer_glue.$recusion_level.$outer_glue, $string);
      
       foreach ($array as $value)
       {
               $row=explode($inner_glue.$recusion_level.$inner_glue,$value);
               $output[$row[0]]=$row[1];
               $level = $recusion_level + 1;
               if(strpos($output[$row[0]],$inner_glue.$level.$inner_glue))
                       $output[$row[0]] = explode_with_keys_a($inner_glue,$outer_glue,$level,$output[$row[0]]);
       }   
      

       return $output;
}
php.net {at} nr78 {dot} net
30-Mar-2005 06:50
Also quite handy in INSERT statements:

<?php

   // array containing data
   $array = array(
      "name" => "John",
      "surname" => "Doe",
      "email" => "j.doe@intelligence.gov"
   );

   // build query...
   $sql  = "INSERT INTO table";

   // implode keys of $array...
   $sql .= " (`".implode("`, `", array_keys($array))."`)";

   // implode values of $array...
   $sql .= " VALUES ('".implode("', '", $array)."') ";

   // execute query...
   $result = mysql_query($sql) or die(mysql_error());

?>
stefan
03-Mar-2005 09:47
Even handier if you use the following:

<?php
$id_nums = array(1,6,12,18,24);

$id_nums = implode(", ", $id_nums);
               
$sqlquery = "Select name,email,phone from usertable where user_id IN ($id_nums)";

// $sqlquery becomes "Select name,email,phone from usertable where user_id IN (1,6,12,18,24)"
?>
Geoff Eby
03-Mar-2005 08:29
A handy use of implode in a MySQL query

<?php
$id_nums = array(1,6,12,18,24);

$id_nums = implode(