HOWTO: Custom Registration Fields

This can be put into functions.php this is simple as it can be

<?php

// This function shows the form fiend on registration page
add_action('register_form','show_first_name_field');

// This is a check to see if you want to make a field required
add_action('register_post','check_fields',10,3);

// This inserts the data
add_action('user_register', 'register_extra_fields');

// This is the forms The Two forms that will be added to the wp register page
function show_first_name_field(){
?>

<p>
<label>First Name<br />
<input id="user_email" class="input" type="text" tabindex="20" size="25" value="<?php echo $_POST['first']; ?>" name="first"/>
</label>
</p>

<p>
<label>Last Name<br />
<input id="user_email" class="input" type="text" tabindex="20" size="25" value="<?php echo $_POST['last']; ?>" name="last"/>
</label>
</p>
<?php
}

// This function checks to see if they didn't enter them
// If no first name or last name display Error
function check_fields($login, $email, $errors) {
	global $firstname, $lastname;
	if ($_POST['first'] == '') {
		$errors->add('empty_realname', "<strong>ERROR</strong>: Please Enter in First Name");
	} else {
		$firstname = $_POST['first'];
	}
	if ($_POST['last'] == '') {
		$errors->add('empty_realname', "<strong>ERROR</strong>: Please Enter in Last Name");
	} else {
		$firstname = $_POST['last'];
	}
}

// This is where the magiv happens
function register_extra_fields($user_id, $password="", $meta=array())  {

// Gotta put all the info into an array
$userdata = array();
$userdata['ID'] = $user_id;

// First name
$userdata['first_name'] = $_POST['first'];

// Last Name
$userdata['last_name'] = $_POST['last'];

// Enters into DB
wp_update_user($userdata);

// This is for custom meta data "gender" is the custom key and M is the value
// update_usermeta($user_id, 'gender','M');

}

?>

I will be posting more at:
https://tipsforwordpress.com/wordpress/add-custom-field-to-register-form/

[[moderated fixed code ]