WP_User_Query

wp_user_query.php

<?php
/**
* WordPress WP_User_Query Comprehensive Reference
* Compiled by wpsmith - wpsmith.net
*
* CODEX: http://codex.wordpress.org/Class_Reference/WP_User_Query
* Source: http://core.trac.wordpress.org/browser/tags/3.4.1/wp-includes/user.php
*/
 
$args = array( 

//////Defaults
    'blog_id' =>                         //(int) - defaults to $GLOBALS['blog_id']
    'role' => '',                        //(string) - 
                                           //Possible Values://
                                             //'subscriber'
                                             //'contributor'
                                             //'author'
                                             //'editor'
                                             //'administrator'
                                             //'custom-role'

//////Meta Query - Custom Field Parameters - Show posts associated with a certain custom field.

    // Simple Meta Query
    'meta_key' => '',                    //(string) - Custom field key.
    'meta_value' => '',                  //(string|array) - Custom field value.
    'meta_compare' => '',                //(string) - Operator to test the 'meta_value'.
                                           //Possible values:// 
                                             //'=', '!=', '>', '>=', '<', '<=', 
                                             //'LIKE', 'NOT LIKE', 'IN', 'NOT IN', 'BETWEEN', 'NOT BETWEEN'
                                             //Default value is '='.
    'meta_type' => '',                   //(string) - Type of meta
                                           //Possible values:// 
                                             //'NUMERIC', 
                                             //'BINARY', 
                                             //'CHAR', 
                                             //'DATE', 
                                             //'DATETIME', 
                                             //'DECIMAL', 
                                             //'SIGNED', 
                                             //'TIME', 
                                             //'UNSIGNED'.

    // Complex Meta Query
    'meta_query' => array(
        array(
            'key'     => 'wpsand_capabilities',
            'value'   => '"author"',
            'compare' => 'not like',
        ),
        array(
            'key'     => '',
            'value'   => '',
            'compare' => '',
        ),
    ),

//////Users Include/Exclude
    'include' => array(),                //(array)  - Array of user IDs to include
    'exclude' => array(),                //(array)  - Array of user IDs to exclude

//////Search Paremeters
    'search' => '',                      //(string) - String value to search for
    'search_columns' => array(),         //(array)  - Array of Table Columns to search
                                            //Possible Values://
                                              //array( 'ID', 'user_login', 'user_email', 'user_url', 'user_nicename' )
                                            //Possible Defaults://
                                              //Defaults to user_email if '@' is present in 'search' arg
                                              //Defaults to user_login & ID if 'search' arg is numeric
                                              //Defaults to user_url if 'search' arg contains http:// or https://
                                              //ELSE Defaults to user_login & user_nicename for strings

//////Order & Orderby Parameters - Sort retrieved posts.
    'orderby' => 'user_login',           //(string) - Sort retrieved users by parameter. Defaults to 'date'.
                                            //Possible Values://
                                              //'user_nicename' OR 'nicename'
                                              //'user_email' OR 'email'
                                              //'user_url' OR 'url'
                                              //'user_registered' OR 'registered'
                                              //'name' OR 'display_name'
                                              //'post_count'
                                              //'ID'
    'order' => 'ASC',                    //(string) - Designates the ascending or descending order of the 'orderby' parameter. Defaultto 'ASC'.
                                           //Possible Values://
                                             //'ASC' - ascending order from lowest to highest values (1, 2, 3; a, b, c).
                                             //'DESC' - descending order from highest to lowest values (3, 2, 1; c, b, a).

//////Offset & Limit Parameters - Useful in pagination
    'offset' => '',                      //(int) - number of users to displace or pass over.
    'number' => '',                      //(int) - number of users to return.

//////Count Parameters (SQL_CALC_FOUND_ROWS)
    'count_total' => true,               //(boolean) - true/false whether to count total.

//////SELECT Parameters
    'fields' => 'all',                   //(string) - Desired fields to appear in the results
                                           //Possible Values://
                                             //'id' - WP_User_Query::get_results() array of IDs
                                             //'all' - WP_User_Query::get_results() array of StdClass Objects (same as get_users)
                                             //'all_with_meta' - WP_User_Query::get_results() array of WP_User Objects
                                             //array( 'ID', 'user_login', 'user_pass', 'user_nicename', 'user_email', 'user_url', 'user_registered', 'user_activation_key', 'user_status', 'display_name' ), // Or, any selection of these

//////User level parameter
    'who' => 'authors',                  //(string) - Retrieves authors, those who have user_levels > 0, Cannot be used with 'meta_key', or 'orderby' => 'meta_value' cf. http://core.trac.wordpress.org/ticket/21581

);

// Create the WP_User_Query object
$user_query = new WP_User_Query( $args );

// Get the results
$authors = $author_query->get_results();
// Output results
foreach( $authors as $author ):
	// do something
endforeach;