implode

(PHP 4, PHP 5, PHP 7, PHP 8)

implodeJoin array elements with a string

Description

implode(string $separator, array $array): string

Alternative signature (not supported with named arguments):

implode(array $array): string

Legacy signature (deprecated as of PHP 7.4.0, removed as of PHP 8.0.0):

implode(array $array, string $separator): string

Join array elements with a separator string.

Parameters

separator

Defaults to an empty string.

array

The array of strings to implode.

Return Values

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

Changelog

Version Description
8.0.0 Passing the separator after the array is no longer supported.
7.4.0 Passing the separator after the array (i.e. using the legacy signature) has been deprecated.

Examples

Example #1 implode() example

<?php

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

echo 
$comma_separated// lastname,email,phone

// Empty string when using an empty array:
var_dump(implode('hello', array())); // string(0) ""

?>

Notes

Note: This function is binary-safe.

See Also

add a note add a note

User Contributed Notes 15 notes

up
334
houston_roadrunner at yahoo dot com
12 years ago
it should be noted that an array with one or no elements works fine. for example:

<?php
    $a1
= array("1","2","3");
   
$a2 = array("a");
   
$a3 = array();
   
    echo
"a1 is: '".implode("','",$a1)."'<br>";
    echo
"a2 is: '".implode("','",$a2)."'<br>";
    echo
"a3 is: '".implode("','",$a3)."'<br>";
?>

will produce:
===========
a1 is: '1','2','3'
a2 is: 'a'
a3 is: ''
up
71
ASchmidt at Anamera dot net
3 years ago
It's not obvious from the samples, if/how associative arrays are handled. The "implode" function acts on the array "values", disregarding any keys:

<?php
declare(strict_types=1);

$a = array( 'one','two','three' );
$b = array( '1st' => 'four', 'five', '3rd' => 'six' );

echo
implode( ',', $a ),'/', implode( ',', $b );
?>

outputs:
one,two,three/four,five,six
up
105
omar dot ajoue at kekanto dot com
8 years ago
Can also be used for building tags or complex lists, like the following:

<?php

$elements
= array('a', 'b', 'c');

echo
"<ul><li>" . implode("</li><li>", $elements) . "</li></ul>";

?>

This is just an example, you can create a lot more just finding the right glue! ;)
up
18
Felix Rauch
5 years ago
It might be worthwhile noting that the array supplied to implode() can contain objects, provided the objects implement the __toString() method.

Example:
<?php

class Foo
{
    protected
$title;

    public function
__construct($title)
    {
       
$this->title = $title;
    }

    public function
__toString()
    {
        return
$this->title;
    }
}

$array = [
    new
Foo('foo'),
    new
Foo('bar'),
    new
Foo('qux')
];

echo
implode('; ', $array);
?>

will output:

foo; bar; qux
up
39
alexey dot klimko at gmail dot com
10 years ago
If you want to implode an array of booleans, you will get a strange result:
<?php
var_dump
(implode('',array(true, true, false, false, true)));
?>

Output:
string(3) "111"

TRUE became "1", FALSE became nothing.
up
56
php.net {at} nr78 {dot} net
16 years ago
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());

?>
up
4
Honk der Hase
1 year ago
If you want to implode an array as key-value pairs, this method comes in handy.
The third parameter is the symbol to be used between key and value.

<?php
function mapped_implode($glue, $array, $symbol = '=') {
    return
implode($glue, array_map(
            function(
$k, $v) use($symbol) {
                return
$k . $symbol . $v;
            },
           
array_keys($array),
           
array_values($array)
            )
        );
}

$arr = [
   
'x'=> 5,
   
'y'=> 7,
   
'z'=> 99,
   
'hello' => 'World',
   
7 => 'Foo',
];

echo
mapped_implode(', ', $arr, ' is ');

// output: x is 5, y is 7, z is 99, hello is World, 7 is Foo

?>
up
21
Anonymous
8 years ago
It may be worth noting that if you accidentally call implode on a string rather than an array, you do NOT get your string back, you get NULL:
<?php
var_dump
(implode(':', 'xxxxx'));
?>
returns
NULL

This threw me for a little while.
up
17
masterandujar
9 years ago
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)"
?>

Be sure to escape/sanitize/use prepared statements if you get the ids from users.
up
4
Anonymous
6 years ago
null values are imploded too. You can use array_filter() to sort out null values.

<?php
$ar
= array("hello", null, "world");
print(
implode(',', $ar)); // hello,,world
print(implode(',', array_filter($ar, function($v){ return $v !== null; }))); // hello,world
?>
up
2
biziclop
7 months ago
Sometimes it's necessary to add a string not just between the items, but before or after too, and proper handling of zero items is also needed.
In this case, simply prepending/appending the separator next to implode() is not enough, so I made this little helper function.

<?php

function wrap_implode( $array, $before = '', $after = '', $separator = '' ){
  if( !
$array )  return '';
  return
$before . implode("{$after}{$separator}{$before}", $array ) . $after;
}

echo
wrap_implode(['path','to','file.php'], '/');
// "/path/to/file.php"

$pattern = '#'. wrap_implode([4,2,2], '\d{', '}', '[-.]') .'#';
echo
$pattern, "\n"// #\d{4}[-.]\d{2}[-.]\d{2}#
echo preg_replace( $pattern, '[REDACTED]', 'The UFO appeared between 2012-12-24 and 2013.01.06 every night.');
// 'The UFO appeared between [REDACTED] and [REDACTED] every night.

echo wrap_implode(['line','by','line'], '<b>', '</b>', '<br>  ');
// <b>line</b><br>  <b>by</b><br>  <b>line</b>

echo wrap_implode( ['<a href="">Menu Item 1</a>', '<a href="">Menu Item 2</a>',],
 
"<li>", "</li>\n",
 
"<li> | </li>\n",
);
/*
<li><a href="">Link1</a></li>
<li> | </li>
<li><a href="">Link2</a></li>
*/

?>
up
-1
info AT sinistercircuits DOT com
21 days ago
There is no mention of behavior on a empty array, so I tried it and here's the result:

<?php
$ar
= array();
$result = implode(',', $ar);  // Comma arbitrarily applied as the separator
$is_result_empty = empty($result);
?>

$result:
$is_result_empty: 1

In other words, an empty string is the result.
up
0
Rafael Pereira
1 year ago
If you want to use a key inside array:

Example:
$arr=array(
array("id" => 1,"name" => "Test1"),
array("id" => 2,"name" => "Test2"),
);

echo implode_key(",",$arr, "name");
OUTPUT: Test1, Test2

function implode_key($glue, $arr, $key){
    $arr2=array();
    foreach($arr as $f){
        if(!isset($f[$key])) continue;
        $arr2[]=$f[$key];
    }
    return implode($glue, $arr2);
}
up
-29
admin at lanlink dot net dot au
4 years ago
It is possible for an array to have numeric values, as well as string values. Implode will convert all numeric array elements to strings.

<?php
$test
=implode(["one",2,3,"four",5.67]);
echo
$test;
//outputs: "one23four5.67"
?>
up
-9
info at ensostudio dot ru
1 year ago
<?php
* Join pieces with a string recursively.
*
* @
param mixed $glue String between pairs(glue) or an array pair's glue and key/value glue or $pieces.
* @param iterable $pieces Pieces to implode (optional).
* @return string Joined string
*/
function double_implode($glue, iterable $pieces = null): string
{
    $glue2 = null;
    if ($pieces === null) {
        $pieces = $glue;
        $glue = '';
    } elseif (is_array($glue)) {
        list($glue, $glue2) = $glue;
    }
   
    $result = [];
    foreach ($pieces as $key => $value) {
        $result[] = $glue2 === null ? $value : $key . $glue2 . $value;
    }
    return implode($glue, $result);
}
?>
Examples:
<?php
$array = ['
a' => 1, 'b' => 2];
$str =  implode($array);
$str =  implode('
, ', $array);
$str =  implode(['" ', '="'], $array);

$iterator = new ArrayIterator($array);
$str =  implode($iterator);
$str =  implode('
, ', $iterator);
$str =  implode(['" ', '="'], $iterator);
?>
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