Wordpress Plugin to Create Custom Registration form Plugin

Wordpress Plugin to Create Custom Registration form Plugin :

<?php

/*
  Plugin Name: Custom Registration Form
  Plugin URI: http://astro-global.blogspot.in/
  Description: Updates user rating based on number of posts.
  Version: 1.0
  Author: Sunil Sharma
  Author URI: https://plus.google.com/u/0/+SunilSharma_007
 */

function custom_registration_function() {
    if (isset($_POST['submit'])) {
        registration_validation(
        $_POST['username'],
        $_POST['password'],
        $_POST['email'],
        $_POST['website'],
        $_POST['fname'],
        $_POST['lname'],
        $_POST['nickname'],
        $_POST['bio']
        );
       
        // sanitize user form input
        global $username, $password, $email, $website, $first_name, $last_name, $nickname, $bio;
        $username    =     sanitize_user($_POST['username']);
        $password     =     esc_attr($_POST['password']);
        $email         =     sanitize_email($_POST['email']);
        $website     =     esc_url($_POST['website']);
        $first_name =     sanitize_text_field($_POST['fname']);
        $last_name     =     sanitize_text_field($_POST['lname']);
        $nickname     =     sanitize_text_field($_POST['nickname']);
        $bio         =     esc_textarea($_POST['bio']);

        // call @function complete_registration to create the user
        // only when no WP_error is found
        complete_registration(
        $username,
        $password,
        $email,
        $website,
        $first_name,
        $last_name,
        $nickname,
        $bio
        );
    }

    registration_form(
        $username,
        $password,
        $email,
        $website,
        $first_name,
        $last_name,
        $nickname,
        $bio
        );
}

function registration_form( $username, $password, $email, $website, $first_name, $last_name, $nickname, $bio ) {
    echo '
    <style>
    div {
        margin-bottom:2px;
    }
   
    input{
        margin-bottom:4px;
    }
    </style>
    ';

    echo '
    <form action="' . $_SERVER['REQUEST_URI'] . '" method="post">
    <div>
    <label for="username">Username <strong>*</strong></label>
    <input type="text" name="username" value="' . (isset($_POST['username']) ? $username : null) . '">
    </div>
   
    <div>
    <label for="password">Password <strong>*</strong></label>
    <input type="password" name="password" value="' . (isset($_POST['password']) ? $password : null) . '">
    </div>
   
    <div>
    <label for="email">Email <strong>*</strong></label>
    <input type="text" name="email" value="' . (isset($_POST['email']) ? $email : null) . '">
    </div>
   
    <div>
    <label for="website">Website</label>
    <input type="text" name="website" value="' . (isset($_POST['website']) ? $website : null) . '">
    </div>
   
    <div>
    <label for="firstname">First Name</label>
    <input type="text" name="fname" value="' . (isset($_POST['fname']) ? $first_name : null) . '">
    </div>
   
    <div>
    <label for="website">Last Name</label>
    <input type="text" name="lname" value="' . (isset($_POST['lname']) ? $last_name : null) . '">
    </div>
   
    <div>
    <label for="nickname">Nickname</label>
    <input type="text" name="nickname" value="' . (isset($_POST['nickname']) ? $nickname : null) . '">
    </div>
   
    <div>
    <label for="bio">About / Bio</label>
    <textarea name="bio">' . (isset($_POST['bio']) ? $bio : null) . '</textarea>
    </div>
    <input type="submit" name="submit" value="Register"/>
    </form>
    ';
}

function registration_validation( $username, $password, $email, $website, $first_name, $last_name, $nickname, $bio )  {
    global $reg_errors;
    $reg_errors = new WP_Error;

    if ( empty( $username ) || empty( $password ) || empty( $email ) ) {
        $reg_errors->add('field', 'Required form field is missing');
    }

    if ( strlen( $username ) < 4 ) {
        $reg_errors->add('username_length', 'Username too short. At least 4 characters is required');
    }

    if ( username_exists( $username ) )
        $reg_errors->add('user_name', 'Sorry, that username already exists!');

    if ( !validate_username( $username ) ) {
        $reg_errors->add('username_invalid', 'Sorry, the username you entered is not valid');
    }

    if ( strlen( $password ) < 5 ) {
        $reg_errors->add('password', 'Password length must be greater than 5');
    }

    if ( !is_email( $email ) ) {
        $reg_errors->add('email_invalid', 'Email is not valid');
    }

    if ( email_exists( $email ) ) {
        $reg_errors->add('email', 'Email Already in use');
    }
   
    if ( !empty( $website ) ) {
        if ( !filter_var($website, FILTER_VALIDATE_URL) ) {
            $reg_errors->add('website', 'Website is not a valid URL');
        }
    }

    if ( is_wp_error( $reg_errors ) ) {

        foreach ( $reg_errors->get_error_messages() as $error ) {
            echo '<div>';
            echo '<strong>ERROR</strong>:';
            echo $error . '<br/>';

            echo '</div>';
        }
    }
}

function complete_registration() {
    global $reg_errors, $username, $password, $email, $website, $first_name, $last_name, $nickname, $bio;
    if ( count($reg_errors->get_error_messages()) < 1 ) {
        $userdata = array(
        'user_login'    =>     $username,
        'user_email'     =>     $email,
        'user_pass'     =>     $password,
        'user_url'         =>     $website,
        'first_name'     =>     $first_name,
        'last_name'     =>     $last_name,
        'nickname'         =>     $nickname,
        'description'     =>     $bio,
        );
        $user = wp_insert_user( $userdata );
        echo 'Registration complete. Goto <a href="' . get_site_url() . '/wp-login.php">login page</a>.';  
    }
}

// Register a new shortcode: [cr_custom_registration]
add_shortcode('cr_custom_registration', 'custom_registration_shortcode');

// The callback function that will replace [book]
function custom_registration_shortcode() {
    ob_start();
    custom_registration_function();
    return ob_get_clean();
}
?>
 

Plugin Usage :

To implement the plugin in a WordPress post or page, use the shortcode[cr_custom_registration].

To implement the registration form in a specific aspect of your theme, add the following template tag - <?php custom_registration_function(); ?>.
You can get the plugin file from the attachment in this article.