How to pass parameter in wordpress url?

WordPress Plugin Development: Is there a meaning to pass an empty array to the second parameter of get_option()?

• I've seen codes passing an empty array to the second parameter of the get_option() function. $data = get_option( 'option_name' , array() ); Is it same as casting to array? Or does it have a special meaning? $data = ( array ) get_option( 'option_name' ); This is the entire get_option() function definition. /** * Retrieve option value based on name of option. * * If the option does not exist or does not have a value, then the return value * will be false. This is useful to check whether you need to install an option * and is commonly used during installation of plugin options and to test * whether upgrading is required. * * If the option was serialized then it will be unserialized when it is returned. * * @since 1.5.0 * @package WordPress * @subpackage Option * @uses apply_filters() Calls 'pre_option_$option' before checking the option. * Any value other than false will "short-circuit" the retrieval of the option * and return the returned value. You should not try to override special options, * but you will not be prevented from doing so. * @uses apply_filters() Calls 'option_$option', after checking the option, with * the option value. * * @param string $option Name of option to retrieve. Expected to not be SQL-escaped. * @param mixed $default Optional. Default value to return if the option does not exist. * @return mixed Value set for the option. */ function get_option( $option, $default = false ) { global $wpdb; $option = trim( $option ); if ( empty( $option ) ) return false; // Allow plugins to short-circuit options. $pre = apply_filters( 'pre_option_' . $option, false ); if ( false !== $pre ) return $pre; if ( defined( 'WP_SETUP_CONFIG' ) ) return false; if ( ! defined( 'WP_INSTALLING' ) ) { // prevent non-existent options from triggering multiple queries $notoptions = wp_cache_get( 'notoptions', 'options' ); if ( isset( $notoptions[$option] ) ) return apply_filters( 'default_option_' . $option, $default ); $alloptions = wp_load_alloptions(); if ( isset( $alloptions[$option] ) ) { $value = $alloptions[$option]; } else { $value = wp_cache_get( $option, 'options' ); if ( false === $value ) { $row = $wpdb->get_row( $wpdb->prepare( "SELECT option_value FROM $wpdb->options WHERE option_name = %s LIMIT 1", $option ) ); // Has to be get_row instead of get_var because of funkiness with 0, false, null values if ( is_object( $row ) ) { $value = $row->option_value; wp_cache_add( $option, $value, 'options' ); } else { // option does not exist, so we must cache its non-existence $notoptions[$option] = true; wp_cache_set( 'notoptions', $notoptions, 'options' ); return apply_filters( 'default_option_' . $option, $default ); } } } } else { $suppress = $wpdb->suppress_errors(); $row = $wpdb->get_row( $wpdb->prepare( "SELECT option_value FROM $wpdb->options WHERE option_name = %s LIMIT 1", $option ) ); $wpdb->suppress_errors( $suppress ); if ( is_object( $row ) ) $value = $row->option_value; else return apply_filters( 'default_option_' . $option, $default ); } // If home is not set use siteurl. if ( 'home' == $option && '' == $value ) return get_option( 'siteurl' ); if ( in_array( $option, array('siteurl', 'home', 'category_base', 'tag_base') ) ) $value = untrailingslashit( $value ); return apply_filters( 'option_' . $option, maybe_unserialize( $value ) ); }

• Answer:

  The second parameter is the default should there be nothing stored in the database. The empty array would be returned if the option was not found allowing for easy testing assuming the option would otherwise have been saved as an array.