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PHP : Function Reference : String Functions : implode

implode

Join array elements with a string (PHP 4, PHP 5)
string implode ( string glue, array pieces )

Join array elements with a glue string.

Note:

implode() can, for historical reasons, accept its parameters in either order. For consistency with explode(), however, it may be less confusing to use the documented order of arguments.

Parameters

glue

Defaults to an empty string. This is not the preferred usage of implode() as glue would be the second parameter and thus, the bad prototype would be used.

pieces

Return Values

Returns a string containing a string representation of all the array elements in the same order, with the glue string between each element.

ChangeLog

Version Description
4.3.0 The glue parameter became optional.

Examples

Example 2416. implode() example

<?php

$array
= array('lastname', 'email', 'phone');
$comma_separated = implode(",", $array);

echo
$comma_separated; // lastname,email,phone

?>


Notes

Note:

This function is binary-safe.

See Also
explode()
split()

Related Examples ( Source code ) » implode








Code Examples / Notes » implode

anajilly

When implode() is passed an array with a single element or
with no elements, it does exactly what you would expect.
<?php
$a = array();      // passed an array with zero elements...
implode(';', $a);  // implode returns an empty string: ''
$a[] = 'n';        // passed an array with one element
implode(';', $a);  // returns the single element value with no $glue used: 'n'
?>


demonisch

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;

}


thomas

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


richard

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


darwinkid

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


gregrahkin

This function will implode a multi-dimension array
function implode_r ($glue, $pieces){
$out = "";
foreach ($pieces as $piece)
 if (is_array ($piece)) $out .= implode_r ($glue, $piece); // recurse
 else                   $out .= $glue.$piece;
 
return $out;
}


sinatosk

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 ;)


static

The one thing missing with this function is a way to add the keys. So I wrote this little function:
function implode_with_keys($glue, $array) {
       $output = array();
       foreach( $array as $key => $item )
               $output[] = $key . "=" . $item;
       return implode($glue, $output);
}


sam dot bledsoe

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("=", ";
$", $arr, "$", ";");
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 = "[" . $key . "]";
       }
//        echo "
";
//        var_dump($item);
//        echo "
";
       $skip_this = false;
       if($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;
 }
}


bishop

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.


andy morris

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 )."
";
echo english_list( array("foo"), 1 )."
";
echo english_list( array("foo", "bar"), 0 )."
";
echo english_list( array("a" => "foo", "b" => "bar", "c" => "foobar"), 1 )."
";
echo english_list( array("foo", "bar", "foobar", "barfoo"), 0 )."
";
?>


ahigerd

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


andy morris

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.


themadbomberwhatbombsatmidnight

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.


klába

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);
}


cedric

Implode with an unset array will made a warning and fail, but is ok with an empty array.
So if you don't trust the content of the array, allways initialize it before :
 $param = array();
 [...]
 echo implode('&', $param);


chris ross

I took static's implode_with_keys, and converted into something I considered a little more programatically useful.  I would argue that this sort of functionality should maybe be added to PHP.
<?php
/* This isn't really DB function, but it's general...  This will */
/* act like the PHP implode() function, but for assoc. arrays... */
function implode_assoc($inner_glue, $outer_glue, $array) {
       $output = array();
       foreach( $array as $key => $item )
               $output[] = $key . $inner_glue . $item;
       return implode($outer_glue, $output);
}
?>
 It's the same as static's, really, but allows you to join the keys to the values with any arbitrary string, rather than hard-coding a '='.


davidpk212

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


info

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.


dennis day

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);


chris

I found it neccesary to create a function that joins the contents of a single dimension from a 2-d array. Here's the code in case anyone else should need to do the same:
<?php
function join_2d($glue, $pieces, $dimension = 0){
//joins the values of a single dimension in a 2-d array
$rtn = array();
foreach($piece as $key => $value){
if(isset($value[$dimension])){
$rtn[] = $value[$dimension];
}
}
return join($glue, $rtn);
}
?>
The dimension argument can be a positive integer or a named index. Here is an example:
<?php
$testarray = array(array(1 => 'a', 'three' => 1),
                         array(1 => 'b', 'three' => 2),
                         array(1 => 'c', 'three' => 3),
                         array(1 => 'd', 'three' => 4),
                         array(1 => 'e', 'three' => 5));
print "<pre>"; print_r($testarray); print "</pre>";
print join_2d(", ", $testarray, 1) . "
";
print join_2d(", ", $testarray, 'three') . "
";
?>


peter dot goodman

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);
}


john

hi,
to prevent implode from putting the zero at the end, I use ksort().
example:
$val[1]="one";
$val[2]="two";
$val[0]="zero";
ksort($val);
echo implode(":",$val);
//will return "zero:one:two"


php

Hey, I found a good use for implode() today. It came from a need to have a <select name=state multiple> box on the page that a person could select multiple states from and send those to a >SELECT * FROM customers WHERE state='$state'; query. But they need to be able to send just one state also. Well, I changes the html select box to say <select name=state[] multiple>. This turns $state into an array as you may know. I then, later on in the script, did this:
$count = count( $state );
if( $count > 1 ) {
    $states = implode( "'.'", $state );
    $result = $database->query( "SELECT * FROM currentOrders WHERE date>=$from AND date <=$to AND state IN ('$states')" );
}
//This takes care of multiple states, but if the user sent only one state, I catch it here:
foreach( $state as $value );
if( $value )
    $result = $database->query( "SELECT * FROM currentOrders WHERE date>=$from AND date<=$to AND state='$value'" );
else //This one will catch the ALL states option if they choose that.
    $result = $database->query( "SELECT * FROM currentOrders WHERE date>=$from AND date<=$to" );
Anyway, I thought I'd post this up here in case it might help someone. Or maybe someone could figure out a better way and enlighten us all.. Have fun.. Bob


triptripon

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


drewish

Here's a pretty clean version of the english_list:
<?php
function english_list($array) {
 switch (count($array)) {
   case 0:
     return '';
   case 1:
     return array_pop($array);
   default:
     $last = array_pop($array);
     return implode(', ', $array) . ' and ' . $last;
 }
}
?>


02-apr-2005 03:07

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;
}


killroy

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);
}


stefan

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)"
?>


peter hopfgartner

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


tshort

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;
}


troy dot cregger

Concerning the function by: darwinkid at gmail dot com... Nice one, I found it useful.  
I made a modification to it though to handle array keys of the form:
array(
   [key1] => one
   [key2] => two
   [key3] => three
)
It also discards empty elements in the array so if you have:
array(
   [key1] => one
   [key2] => two
   [key3] => three
   [key4] =>
   [key5] => five
)
You'd get:
one,two,three,five
rather than:
one, two, three, ,five
If you supply ", " as glue.
Here's my code:
<?php
function my_implode_by_key($glue, $key, $pieces) {
$it = new RecursiveIteratorIterator(new RecursiveArrayIterator($pieces));
foreach($it as $el) {if(substr($it->key(), 0, 3) == $key && $it->current() != '') {$arr[] = $it->current();}}
return implode($glue, $arr);
}
?>


hotmail resident tree2054

Combining into one function:
function implode_with_options($assoc_array, $prefix = '', $k_v_glue = '', $vwrap = '', $seperator = '')
{
  foreach ($assoc_array as $k => $v)
  {
      $tmp[] = $k . $k_v_glue . $vwrap . $v . $vwrap;
  }
  return $prefix . implode($seperator, $tmp);
}
$items = array('Apples', 'number' => 3, 'Vehicle' => '');
// For a query string:
echo implode_with_options($items, '?', '=', '', '&');
/**
* Produces
* ?0=Apples&number=3&Vehicle=
*/
// For a SQL query
echo implode_with_options($items, '', '=', '"', ', ');
/**
* Produces
* 0="Apples", number="3", Vehicle=""
*/


phpwalter

Chris Ross (17-Aug-2004 11:18) gave us a great function 'implode_assoc'.
But it didn't handle multi-level array.
I know, a few others here added this "feature", but...
I've modified Chirs' function to be recursive.
Hope it helps someone.
/**
 * Method to recursivly implode a multi-dimensional array
 * Orginal: Chris Ross - 17-Aug-2004
 * Modified: Walter Torres - 09-14-2004
 **/
function implode_assoc_r($inner_glue = "=", $outer_glue = "\n", $array = null, $keepOuterKey = false)
{
$output = array();
foreach( $array as $key => $item )
if ( is_array ($item) )
{
if ( $keepOuterKey )
$output[] = $key;
// This is value is an array, go and do it again!
$output[] = implode_assoc_r ($inner_glue, $outer_glue, $item, $keepOuterKey);
}
else
$output[] = $key . $inner_glue . $item;
return implode($outer_glue, $output);
}


1413

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()).'
';
  print ImplodeProper(array('foo')).'
';
  print ImplodeProper(array('foo','bar')).'
';
  print ImplodeProper(array('for','bar','bleh')).'
';
?>
Yields:
foo
foo, and bar
for, bar, and bleh


james

As a followup to the implode_with_keys function posted by 'static', here's a corresponding explode_with_keys function I wrote:
function explode_with_keys($seperator, $string)
{
       $output=array();
       $array=explode($seperator, $string);
       foreach ($array as $value) {
               $row=explode("=",$value);
               $output[$row[0]]=$row[1];
       }
       return $output;
}


php

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;
 }
?>


hayley

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;
}
}
?>


dabduster

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);
}


adnan

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' */
?>


php.net {at} nr78 {dot} net

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());
?>


brian

A simple extension to implode, which includes a second gluing of keys.  Particularly handy when managing $_GET and $_POST.
<?
function implode_assoc($glue1, $glue2, $array){
foreach($array as $key => $val)
$array2[] = $key.$glue1.$val;
return implode($glue2, $array2);
}
//usage:
$array["key"]="val";
$array["key2"]="val2";
implode_assoc("=", "&", $array); //returns "key=val&key2=val2"
?>


worldwideweb dot c-kling dot de

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);
}
}
?>


pr10n

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));
}
?>


geoff eby

A handy use of implode in a MySQL query
<?php
$id_nums = array(1,6,12,18,24);
$id_nums = implode(" OR user_id=", $id_nums);

$sqlquery = "Select name,email,phone from usertable where user_id=$id_nums";
// $sqlquery becomes "Select name,email,phone from usertable where user_id=1 OR user_id=6 OR user_id=12 OR user_id=18 OR user_id=24"
?>


memandeemail

/**
* 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);
}


tshort

/*
 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;
}


cristiandotzuddas

...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);
}
?>


adrian

...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'


dan

*** MULTI-DIMENSIONAL ARRAY IMPLODE ***
First of all, it should be noted that the function in the previous note is not technically correct, as it glues the outside of the first piece. This is the problem faced by any function that wants to construct a set out of an array without the overhead of handling the boundary indexes. It also doesn't preserve the dimensional architecture.
Use this function when you want to call implode() on a multi-dimensional array and want the resulting string to preserve the architecture of the different dimensions. For example:
array ( 5, array (2, 4, 6), array (3, 6, 9, array (12)))
would be reduced to:
[ 5, [ 2, 4, 6 ], [ 3, 6, 9, [ 12 ] ] ]
Note that this does not preserve key values. If you need those, you are probably better off using serialize() and then replacing the tokens with your own symbols using the string functions.
Anyway, here is the code:
function mdImpode($x, $y)
{
$a = (is_array($x)) ? '[ ' . array_reduce($x, 'mdImplode') . ' ]' : $x;
$b = (is_array($y)) ? '[ ' . array_reduce($y, 'mdImplode') . ' ]' : $y;
return $a . ', ' . $b;
}
Then to call it, use:
$result = '[ ' . array_reduce($pieces, 'mdImplode') . ' ]';
Note that you have to make manual changes if you want different glue or set symbols. There may be a more elegant solution, but this should be a good compromise between efficiency and simplicity (the manual says that array_reduce is iterative, so this should be pretty speedy).


ulderico

'Implode' does not implodes recursively... It might quite useful implode recursively when you get a many Arrays values with keys that replaces themselves as:
http://server/file.php?arg[1]=123&arg[2]=312&arg[3]=543&arg[2]=abc
If you build this URL progressively it would a great a idea that the newest value indeed took the place of any older ones, thus:
http://server/file.php?arg[1]=123&arg[3]=543&arg[2]=abc
would be a better option;
If one uses $_SERVER['REQUEST_URI'], this sanitation would not happen, the URL string would be greater and greater everytime.
With implode_r (see below) it becomes easier to build a "sanitised" URL, the one that less likely will overflow the browser.
$URL = $_SERVER['PHP_SELF'];
$tmp = implode_r("&", $_REQUEST); /* So as to allow to get ANY VALUE (G/P) from the Browser... */
$URL .= "?".$tmp;
/* implode_r */
function implode_r($glue, $array, $array_name = NULL){
while(list($key,$value) = @each($array))
if(is_array($value))
                       $return[] = implode_r($glue, $value, (string) $key);
               else
                       if($array_name != NULL)
                               $return[] = $array_name."[".(string) $key."]=".$value;
                       else
                               $return[] = $key."=".$value;
                               
       return(implode($glue, $return));
}
sorry I couldn't format the code.


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