(PHP 4, PHP 5, PHP 7, PHP 8)
implode — Join array elements with a string
Alternative signature (not supported with named arguments):
Legacy signature (deprecated as of PHP 7.4.0, removed as of PHP 8.0.0):
Join array elements with a separator string.
separatorOptional. Defaults to an empty string.
arrayThe array of strings to implode.
Returns a string containing a string representation of all the array elements in the same order, with the separator string between each element.
| 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.
|
Example #1 implode() example
<?php
$array = ['lastname', 'email', 'phone'];
var_dump(implode(",", $array)); // string(20) "lastname,email,phone"
// Empty string when using an empty array:
var_dump(implode('hello', [])); // string(0) ""
// The separator is optional:
var_dump(implode(['a', 'b', 'c'])); // string(3) "abc"
?>Note: This function is binary-safe.
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: ''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,sixCan 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! ;)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('; ', $array);
?>
will output:
foo; bar; quxIf you want to implode an array of booleans, you will get a strange result:
<?php
var_dump(implode('',array(true, true, false, false, true)));
?>
Output:
string(3) "111"
TRUE became "1", FALSE became nothing.If you want to implode an array as key-value pairs, this method comes in handy.
The third parameter is the symbol to be used between key and value.
<?php
function mapped_implode($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
?>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.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.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
?>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>
*/
?>