| Function name | Parameters | Description |
| add_post | $post_info, &$new_pid | Creates a new post |
| add_topic | $post_info, &$new_tid, &$new_pid | Creates a new topic with its first post |
| add_user | $user_info, &$new_uid | Adds a new user. The username must be passed through validate_username() first. |
| array_insert | &$input, $offset, $element, $key = null | Inserts $element into $input at $offset |
| authenticate_user | $user, $password, $password_is_hash = false | Authenticates the provided username and password against the user database |
| censor_words | $text | Replace censored words in $text |
| check_bans | | Check whether the connecting user is banned (and delete any expired bans while we're at it) |
| check_username_dupe | $username, $exclude_id = null | Check if a username is occupied |
| clean_forum_moderators | | Iterates through all forum moderator lists and removes any erroneous entries |
| clean_version | $version | Clean version string from trailing '.0's |
| cookie_login | &$forum_user | Attempt to login with the user ID and password hash from the cookie |
| csrf_confirm_form | | Display a form that the user can use to confirm that they want to undertake an action. Used when the CSRF token from the request does not match the token stored in the database. |
| delete_avatar | $user_id | Deletes any avatars owned by the specified user ID |
| delete_orphans | | Locate and delete any orphaned redirect topics |
| delete_post | $post_id, $topic_id, $forum_id | Delete a single post |
| delete_topic | $topic_id, $forum_id | Delete a topic and all of it's posts |
| delete_user | $user_id | Delete a user and all information associated with it |
| dump | $arg1, … | Dump contents of variable(s) |
| error | | Display a simple error message |
| format_time | $timestamp, $date_only = false | Format a time string according to $time_format and timezones |
| forum_clear_cache | | Delete every .php file in the forum's cache directory |
| forum_hash | $str, $salt | Generates a salted, SHA-1 hash of $str |
| forum_htmlencode | $str | Encodes the contents of $str so that they are safe to output on an (X)HTML page |
| forum_linebreaks | $str | Convert rn and r to n |
| forum_link | $link, $args = null | Generate a hyperlink with parameters and anchor |
| forum_setcookie | $name, $value, $expire | Set a cookie, FluxBB style! |
| forum_strlen | $str | An UTF-8 aware version of strlen() |
| forum_sublink | $link, $sublink, $subarg, $args = null | Generate a hyperlink with parameters and anchor and a subsection such as a subpage |
| forum_unregister_globals | | Unset any variables instantiated as a result of register_globals being enabled |
| generate_avatar_markup | $user_id | Generates the HTML code to display the users avatar |
| generate_crumbs | $reverse | Generate breadcrumb navigation |
| generate_form_token | $target_url | Generates a valid CSRF token for use when submitting a form to $target_url. $target_url should be an absolute URL and it should be exactly the URL that the user is going to. Alternately, if the form token is going to be used in GET (which would mean the token is going to be a part of the URL itself), $target_url may be a plain string containing information related to the URL. |
| generate_navlinks | | Generate the “navigator” that appears at the top of every page |
| generate_profile_menu | | Display the profile navigation menu |
| get_current_url | $max_length = 0 | Try to determine the current URL |
| get_hook | $hook_id | Return all code blocks that hook into $hook_id |
| get_remote_address | | Try to determine the correct remote IP-address |
| get_remote_file | $url, $timeout, $head_only = false | Attempts to fetch the provided URL using any available means |
| get_saved_queries | | Display executed queries (if enabled) |
| get_title | $user | Determines the correct title for $user. $user must contain the elements 'username', 'title', 'posts', 'g_id' and 'g_user_title' |
| get_tracked_topics | | Extract array of tracked topics from cookie |
| maintenance_message | | Display a message when board is in maintenance mode |
| message | $message, $link = '' | Display a message |
| paginate | $num_pages, $cur_page, $link, $separator, $args = null | Generate a string with numbered links (for multipage scripts) |
| random_key | $len, $readable = false, $hash = false | Generate a random key of length $len |
| redirect | $destination_url, $message | Display $message and redirect user to $destination_url |
| sef_friendly | $str | Make a string safe to use in a URL |
| send_subscriptions | $post_info, $new_pid | Send out subscription emails |
| set_default_user | | Fill $forum_user with default values (for guests) |
| set_tracked_topics | $tracked_topics | Save array of tracked topics in cookie |
| sync_forum | $forum_id | Update posts, topics, last_post, last_post_id and last_poster for a forum |
| sync_topic | $topic_id | Update replies, last_post, last_post_id and last_poster for a topic |
| update_users_online | | Update “Users online” |
| validate_username | $username, $exclude_id = null | Verifies that the provided username is OK for insertion into the database |
