PHP explode(): Split a String into an Array

explode($separator, $string) splits a string at every occurrence of $separator and returns the pieces as an array. explode(',', 'apple,banana,cherry') gives ['apple', 'banana', 'cherry'].

<?php
$csv = 'apple,banana,cherry';
$fruits = explode(',', $csv);

print_r($fruits);
echo $fruits[1], "\n";
echo count($fruits), " fruits\n";

The separator can be any string, not just one character: explode(' and ', 'tea and milk and sugar') works the same way. The opposite operation, joining an array back into a string, is implode().

Syntax and return value

explode(string $separator, string $string, int $limit = PHP_INT_MAX): array

It always returns an array. If the separator does not appear, the array holds the whole string as its only element. That includes the empty string, which gives an array with one empty string in it, a common source of "my loop runs once on empty input" bugs.

<?php
var_dump(explode(',', 'apple'));   // separator not found
var_dump(explode(',', ''));        // empty input
var_dump(explode(',', 'a,,b,'));   // empty pieces are kept

// If an empty string should mean "no items", check before splitting
$input = '';
$tags = $input === '' ? [] : explode(',', $input);
echo count($tags), "\n";

Limit the number of pieces

The third argument, $limit, changes how many pieces you get:

• A positive limit returns at most that many pieces. The last piece holds the rest of the string, separators included.
• A negative limit returns every piece except the last abs($limit) ones.
• A limit of 0 is treated as 1.

<?php
$path = 'home/ada/projects/site/index.php';

print_r(explode('/', $path, 2));   // first piece, then the rest
print_r(explode('/', $path, -1));  // everything except the file name
print_r(explode('/', $path, 0));   // treated as 1

A positive limit is the right tool when only the first separator matters, for example a key=value line where the value may contain = too: explode('=', 'query=a=b', 2) gives ['query', 'a=b']. The next sections use it that way.

To get only the last piece, store the array in a variable first: $parts = explode('/', $path); $file = end($parts);. Writing end(explode('/', $path)) still returns the right value, but PHP prints Notice: Only variables should be passed by reference, because end() takes its argument by reference.

Split a string by newline

explode("\n", $text) splits at line breaks. Use double quotes: in single quotes '\n' is a backslash followed by the letter n, not a newline. Text from Windows files or HTML forms often ends lines with "\r\n", which leaves a stray "\r" at the end of each piece. preg_split('/\R/', $text) splits at any kind of line break.

<?php
$text = "first line\r\nsecond line\nthird line";

$pieces = explode("\n", $text);
var_dump($pieces[0]);   // still ends with \r

$lines = preg_split('/\R/', $text);
var_dump($lines);

Trim the pieces and drop empty ones

User input like "red, green , ,blue" has spaces around the items and an empty item in the middle. Pass the pieces through trim() with array_map(), then remove empty strings with array_filter(). array_values() renumbers the keys afterwards, because array_filter() keeps the original ones.

<?php
$input = 'red, green , ,blue';

$colors = array_map('trim', explode(',', $input));
$colors = array_values(array_filter($colors, fn($c) => $c !== ''));

print_r($colors);

The callback fn($c) => $c !== '' keeps the string "0". A bare array_filter($colors) would drop it, because "0" is falsy.

Turn a string into an associative array

Settings, cookies and query-like strings are often stored as key=value pairs. Explode twice: once for the pairs, once for each pair with a limit of 2, unpacking the two pieces into variables (array destructuring).

<?php
$settings = 'theme=dark;lang=ja;filter=a=b';

$result = [];
foreach (explode(';', $settings) as $pair) {
    [$key, $value] = explode('=', $pair, 2);
    $result[$key] = $value;
}

print_r($result);
echo $result['lang'], "\n";

A pair with no = in it, such as debug, gives a one-element array, and the destructuring prints Warning: Undefined array key 1. Pad the result to two elements to avoid it: [$key, $value] = explode('=', $pair, 2) + [1 => ''];.

For a real URL query string, parse_str() does this for you and also decodes %20 and +.

Split by several delimiters

explode() takes one separator. To split at commas, semicolons or spaces, use preg_split() with a character class. PREG_SPLIT_NO_EMPTY drops the empty pieces that two delimiters in a row would create.

<?php
$input = 'php, javascript;python  go|rust';

$words = preg_split('/[\s,;|]+/', $input, -1, PREG_SPLIT_NO_EMPTY);
print_r($words);

Japanese and other UTF-8 text

explode() compares bytes, and in UTF-8 a full character never appears inside another character's bytes, so splitting Japanese text at a Japanese separator such as 、 or a full-width comma works correctly.

<?php
$cities = '東京、大阪、京都';
print_r(explode('、', $cities));

// Split into single characters: mb_str_split counts characters, str_split counts bytes
print_r(mb_str_split('日本語'));

explode vs str_split vs preg_split

explode() does no regex work, so it is faster than preg_split() and the one to reach for whenever the separator is a fixed string.

Common mistake: an empty separator

An empty separator is an error. Since PHP 8.0 explode('', 'abc') throws a ValueError instead of returning false, and the script stops:

PHP Fatal error:  Uncaught ValueError: explode(): Argument #1 ($separator) cannot be empty in /home/index.php:3

To split a string into characters, use str_split('abc') for ASCII text or mb_str_split($s) for anything that may contain multibyte characters.