Change the display name for Member Directory and Profile Pages Add On

my-pmpro-change-display-name-member-directory.php

<?php
/**
 * Replace a user's display name on directory and profile page with their full name.
 * This requires the latest version (1.0+) of the Member Directory and Profile Pages Add On - https://www.paidmembershipspro.com/add-ons/member-directory/
 *
 * Add this code to your site by following this guide - https://www.paidmembershipspro.com/create-a-plugin-for-pmpro-customizations/
 */
function my_pmpro_member_directory_change_display_name( $display_name, $user ) {
    $first_name = isset( $user->first_name ) ? $user->first_name : get_user_meta( $user->ID, 'first_name', true );
    $last_name = isset( $user->last_name ) ? $user->last_name : get_user_meta( $user->ID, 'last_name', true );

    if ( ! empty( $first_name ) && ! empty( $last_name ) ) {
        $display_name = $first_name . ' ' . $last_name;
    }

    return $display_name;
}
add_filter( 'pmpro_member_directory_display_name', 'my_pmpro_member_directory_change_display_name', 10, 2 );