Author: Purab

In wordpress theming is very important. Developers know the importance of functions.php file. Here we given most used wordpress functions in theme which will be useful for wordpress developer. I always written some very nice code snippets in functions.php file.

most used wordpress functions in theme

I found very useful codes which is very helpful for very wordpress designer and developers.

Here is very useful code snippets.
Enable Hidden Admin Feature displaying ALL Site Settings

// CUSTOM ADMIN MENU LINK FOR ALL SETTINGS
   function all_settings_link() {
    add_options_page(__('All Settings'), __('All Settings'), 'administrator', 'options.php');
   }
   add_action('admin_menu', 'all_settings_link');

Remove Update Notification for all users except ADMIN User

// REMOVE THE WORDPRESS UPDATE NOTIFICATION FOR ALL USERS EXCEPT SYSADMIN
       global $user_login;
       get_currentuserinfo();
       if (!current_user_can('update_plugins')) { // checks to see if current user can update plugins
        add_action( 'init', create_function( '$a', "remove_action( 'init', 'wp_version_check' );" ), 2 );
        add_filter( 'pre_option_update_core', create_function( '$a', "return null;" ) );
       }

Include custom post types in the search results.

// MAKE CUSTOM POST TYPES SEARCHABLE
function searchAll( $query ) {
 if ( $query->is_search ) { $query->set( 'post_type', array( 'site','plugin', 'theme','person' )); }
 return $query;
}
add_filter( 'the_search_query', 'searchAll' );

Add your custom post types to your sites main RSS feed by default.

// ADD CUSTOM POST TYPES TO THE DEFAULT RSS FEED
function custom_feed_request( $vars ) {
 if (isset($vars['feed']) && !isset($vars['post_type']))
  $vars['post_type'] = array( 'post', 'site', 'plugin', 'theme', 'person' );
 return $vars;
}
add_filter( 'request', 'custom_feed_request' );

Modify the Login Logo & Image URL Link

add_filter( 'login_headerurl', 'namespace_login_headerurl' );
/**
 * Replaces the login header logo URL
 *
 * @param $url
 */
function namespace_login_headerurl( $url ) {
    $url = home_url( '/' );
    return $url;
}

add_filter( 'login_headertitle', 'namespace_login_headertitle' );
/**
 * Replaces the login header logo title
 *
 * @param $title
 */
function namespace_login_headertitle( $title ) {
    $title = get_bloginfo( 'name' );
    return $title;
}

add_action( 'login_head', 'namespace_login_style' );
/**
 * Replaces the login header logo
 */
function namespace_login_style() {
    echo '<style>.login h1 a { background-image: url( ' . get_template_directory_uri() . '/images/logo.png ) !important; }</style>';
}

Loading jQuery from the Google CDN

// even more smart jquery inclusion :)
add_action( 'init', 'jquery_register' );

// register from google and for footer
function jquery_register() {

if ( !is_admin() ) {

    wp_deregister_script( 'jquery' );
    wp_register_script( 'jquery', ( 'https://ajax.googleapis.com/ajax/libs/jquery/1.7.1/jquery.min.js' ), false, null, true );
    wp_enqueue_script( 'jquery' );
}
}

Remove the WordPress Version Info for Security

// remove version info from head and feeds
function complete_version_removal() {
    return '';
}
add_filter('the_generator', 'complete_version_removal');

Add Spam & Delete Links to Comments on Front End

// spam & delete links for all versions of wordpress
function delete_comment_link($id) {
    if (current_user_can('edit_post')) {
        echo '| <a href="'.get_bloginfo('wpurl').'/wp-admin/comment.php?action=cdc&c='.$id.'">del</a> ';
        echo '| <a href="'.get_bloginfo('wpurl').'/wp-admin/comment.php?action=cdc&dt=spam&c='.$id.'">spam</a>';
    }
}

Remove Default WordPress Meta Boxes

// REMOVE META BOXES FROM DEFAULT POSTS SCREEN
   function remove_default_post_screen_metaboxes() {
 remove_meta_box( 'postcustom','post','normal' ); // Custom Fields Metabox
 remove_meta_box( 'postexcerpt','post','normal' ); // Excerpt Metabox
 remove_meta_box( 'commentstatusdiv','post','normal' ); // Comments Metabox
 remove_meta_box( 'trackbacksdiv','post','normal' ); // Talkback Metabox
 remove_meta_box( 'slugdiv','post','normal' ); // Slug Metabox
 remove_meta_box( 'authordiv','post','normal' ); // Author Metabox
 }
   add_action('admin_menu','remove_default_post_screen_metaboxes');

// REMOVE META BOXES FROM DEFAULT PAGES SCREEN
   function remove_default_page_screen_metaboxes() {
 remove_meta_box( 'postcustom','page','normal' ); // Custom Fields Metabox
 remove_meta_box( 'postexcerpt','page','normal' ); // Excerpt Metabox
 remove_meta_box( 'commentstatusdiv','page','normal' ); // Comments Metabox
 remove_meta_box( 'trackbacksdiv','page','normal' ); // Talkback Metabox
 remove_meta_box( 'slugdiv','page','normal' ); // Slug Metabox
 remove_meta_box( 'authordiv','page','normal' ); // Author Metabox
 }
   add_action('admin_menu','remove_default_page_screen_metaboxes');

Add Custom User Profile Fields

// CUSTOM USER PROFILE FIELDS
   function my_custom_userfields( $contactmethods ) {

    // ADD CONTACT CUSTOM FIELDS
    $contactmethods['contact_phone_office']     = 'Office Phone';
    $contactmethods['contact_phone_mobile']     = 'Mobile Phone';
    $contactmethods['contact_office_fax']       = 'Office Fax';

    // ADD ADDRESS CUSTOM FIELDS
    $contactmethods['address_line_1']       = 'Address Line 1';
    $contactmethods['address_line_2']       = 'Address Line 2 (optional)';
    $contactmethods['address_city']         = 'City';
    $contactmethods['address_state']        = 'State';
    $contactmethods['address_zipcode']      = 'Zipcode';
    return $contactmethods;
   }
   add_filter('user_contactmethods','my_custom_userfields',10,1);

Add an excerpt box for pages

if ( function_exists('add_post_type_support') )
{
    add_action('init', 'add_page_excerpts');
    function add_page_excerpts()
    {
        add_post_type_support( 'page', 'excerpt' );
    }
}

Function to change the length of Exerpt

function new_excerpt_length($length) {
    return 100;
}

add_filter('excerpt_length', 'new_excerpt_length');

Auto Extract the First Image from the Post Content

/ AUTOMATICALLY EXTRACT THE FIRST IMAGE FROM THE POST
function getImage($num) {
    global $more;
    $more = 1;
    $link = get_permalink();
    $content = get_the_content();
    $count = substr_count($content, '<img');
    $start = 0;
    for($i=1;$i<=$count;$i++) {
        $imgBeg = strpos($content, '<img', $start);
        $post = substr($content, $imgBeg);
        $imgEnd = strpos($post, '>');
        $postOutput = substr($post, 0, $imgEnd+1);
        $postOutput = preg_replace('/width="([0-9]*)" height="([0-9]*)"/', '',$postOutput);;
        $image[$i] = $postOutput;
        $start=$imgEnd+1;
    }
    if(stristr($image[$num],'<img')) { echo '<a href="'.$link.'">'.$image[$num]."</a>"; }
    $more = 0;
}

Unregister WP Default Widgets

// unregister all default WP Widgets
function unregister_default_wp_widgets() {
    unregister_widget('WP_Widget_Pages');
    unregister_widget('WP_Widget_Calendar');
    unregister_widget('WP_Widget_Archives');
    unregister_widget('WP_Widget_Links');
    unregister_widget('WP_Widget_Meta');
    unregister_widget('WP_Widget_Search');
    unregister_widget('WP_Widget_Text');
    unregister_widget('WP_Widget_Categories');
    unregister_widget('WP_Widget_Recent_Posts');
    unregister_widget('WP_Widget_Recent_Comments');
    unregister_widget('WP_Widget_RSS');
    unregister_widget('WP_Widget_Tag_Cloud');
}
add_action('widgets_init', 'unregister_default_wp_widgets', 1);

Enable GZIP output compression

if(extension_loaded("zlib") && (ini_get("output_handler") != "ob_gzhandler"))
   add_action('wp', create_function('', '@ob_end_clean();@ini_set("zlib.output_compression", 1);'));

Enable shortcodes in widgets

// shortcode in widgets
if ( !is_admin() ){
    add_filter('widget_text', 'do_shortcode', 11);
}

If you have any interesting code snippets then please suggest me.