most used wordpress functions in theme

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.