How to join filesystem path strings in PHP?

function join_paths() {
    $paths = array();

    foreach (func_get_args() as $arg) {
        if ($arg !== '') { $paths[] = $arg; }
    }

    return preg_replace('#/+#','/',join('/', $paths));
}

My solution is simpler and more similar to the way Python os.path.join works

Consider these test cases

array               my version    @deceze      @david_miller    @mark

['','']             ''            ''           '/'              '/'
['','/']            '/'           ''           '/'              '/'
['/','a']           '/a'          'a'          '//a'            '/a'
['/','/a']          '/a'          'a'          '//a'            '//a'
['abc','def']       'abc/def'     'abc/def'    'abc/def'        'abc/def'
['abc','/def']      'abc/def'     'abc/def'    'abc/def'        'abc//def'
['/abc','def']      '/abc/def'    'abc/def'    '/abc/def'       '/abc/def'
['','foo.jpg']      'foo.jpg'     'foo.jpg'    '/foo.jpg'       '/foo.jpg'
['dir','0','a.jpg'] 'dir/0/a.jpg' 'dir/a.jpg'  'dir/0/a.jpg'    'dir/0/a.txt'

My take:

function trimds($s) {
    return rtrim($s,DIRECTORY_SEPARATOR);
}

function joinpaths() {
    return implode(DIRECTORY_SEPARATOR, array_map('trimds', func_get_args()));
}

I'd have used an anonymous function for trimds, but older versions of PHP don't support it.

Example:

join_paths('a','\\b','/c','d/','/e/','f.jpg'); // a\b\c\d\e\f.jpg (on Windows)

---

Updated April 2013 March 2014 May 2018:

function join_paths(...$paths) {
    return preg_replace('~[/\\\\]+~', DIRECTORY_SEPARATOR, implode(DIRECTORY_SEPARATOR, $paths));
}

This one will correct any slashes to match your OS, won't remove a leading slash, and clean up and multiple slashes in a row.

Since this seems to be a popular question and the comments are filling with "features suggestions" or "bug reports"... All this code snippet does is join two strings with a slash without duplicating slashes between them. That's all. No more, no less. It does not evaluate actual paths on the hard disk nor does it actually keep the beginning slash (add that back in if needed, at least you can be sure this code always returns a string without starting slash).

join('/', array(trim("abc/de/", '/'), trim("/fg/x.php", '/')));

The end result will always be a path with no slashes at the beginning or end and no double slashes within. Feel free to make a function out of that.

EDIT: Here's a nice flexible function wrapper for above snippet. You can pass as many path snippets as you want, either as array or separate arguments:

function joinPaths() {
    $args = func_get_args();
    $paths = array();
    foreach ($args as $arg) {
        $paths = array_merge($paths, (array)$arg);
    }

    $paths = array_map(create_function('$p', 'return trim($p, "/");'), $paths);
    $paths = array_filter($paths);
    return join('/', $paths);
}

echo joinPaths(array('my/path', 'is', '/an/array'));
//or
echo joinPaths('my/paths/', '/are/', 'a/r/g/u/m/e/n/t/s/');

:o)

@deceze's function doesn't keep the leading / when trying to join a path that starts with a Unix absolute path, e.g. joinPaths('/var/www', '/vhosts/site');.

function unix_path() {
  $args = func_get_args();
  $paths = array();

  foreach($args as $arg) {
    $paths = array_merge($paths, (array)$arg);
  }

  foreach($paths as &$path) {
    $path = trim($path, '/');
  }

  if (substr($args[0], 0, 1) == '/') {
    $paths[0] = '/' . $paths[0];
  }

  return join('/', $paths);
}