How to join array elements in PHP?

Use implode($separator, $array). Example: implode(', ', ['a','b','c']) returns 'a, b, c'.

Can implode() work with associative arrays?

Yes, but implode() only joins values, not keys. Use array_keys() if you need keys.

join() is an alias of implode(). They work identically.

String Function PHP 4+

The implode() function joins array elements into a single string using a separator.

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

Parameter	Type	Description
`$separator`	string	The glue string between elements
`$array`	array	The array of strings to join

Returns a string containing all array elements joined by the separator.

Output

Click Run to execute your code

<?php
$data = ["John", "25", "NYC"];
echo implode(",", $data);
// "John,25,NYC"
?>

<?php
$ids = [1, 2, 3, 4];
$sql = "SELECT * FROM users WHERE id IN (" . implode(",", $ids) . ")";
echo $sql;
?>

<?php
$chars = ["H", "e", "l", "l", "o"];
echo implode("", $chars);  // "Hello"
?>

Tip: join() is an alias of implode() - they work identically.