function random_string($length) {
$key = '';
$keys = array_merge(range(0, 9), range('a', 'z'));
for ($i = 0; $i < $length; $i++) {
$key .= $keys[array_rand($keys)];
}
return $key;
}
echo random_string(50);
Example output:
zsd16xzv3jsytnp87tk7ygv73k8zmr0ekh6ly7mxaeyeh46oe8
EDIT
Make this unique in a directory, changes to function here:
function random_filename($length, $directory = '', $extension = '')
{
// default to this files directory if empty...
$dir = !empty($directory) && is_dir($directory) ? $directory : dirname(__FILE__);
do {
$key = '';
$keys = array_merge(range(0, 9), range('a', 'z'));
for ($i = 0; $i < $length; $i++) {
$key .= $keys[array_rand($keys)];
}
} while (file_exists($dir . '/' . $key . (!empty($extension) ? '.' . $extension : '')));
return $key . (!empty($extension) ? '.' . $extension : '');
}
// Checks in the directory of where this file is located.
echo random_filename(50);
// Checks in a user-supplied directory...
echo random_filename(50, '/ServerRoot/mysite/myfiles');
// Checks in current directory of php file, with zip extension...
echo random_filename(50, '', 'zip');