Add new fields in joomla registration form

Let us add a custom field phone and mobile in registration form
libraries\joomla\database\table\user.php it’s the class file tor user table/user object
function __construct( &$db )
//add new field
var $phone = null;
var $mobile= null;
after that open
libraries\joomla\libraries\joomla\user\user.php
//add this code
var $phone = null;
var $mobile= null;
Add two fields in users table

ALTER TABLE jos_users ADD phone varchar(255) DEFAULT '' 
AFTER password;
ALTER TABLE jos_users ADD mobile varchar(255) DEFAULT '' 
AFTER phone;

Now go to Now go to administrator\components\com_users\views\
user\tmpl

<tr>
<td width="150">
<label for="phone">
 <?php echo JText::_( 'Phone' ); ?>
</label>
</td>
<td>
<input type="text" name="phone" id="phone" size="40"
 value="<?php echo $this->user->get('phone'); ?>" />
</td>
</tr>
<tr><td width="150">
<label for="mobile">
<?php echo JText::_( 'Mobile' ); ?>
</label>
</td>
<td>
<input type="text" name="mobile" id="mobile" size="40"
value="<?php echo $this->user->get('mobile'); ?>" />
</td>
</tr>
Also in components\com_user\views\register\tmpl
 
<tr>
<td height="40">
<label id="phonemsg" for="phone">
<?php echo JText::_( 'Phone' ); ?>:
</label>
</td>
<td>
<input type="text" name="phone" id="phone" size="40"
 value="<?php echo $this->escape($this->user->get( 'phone' ));?>" 
maxlength="50" /> *
</td>
</tr>
<tr>
<td height="40">
<label id="websitemsg" for="mobile">
<?php echo JText::_( 'Mobile' ); ?>:
</label>
</td>
<td>
<input type="text" name="mobile" id="mobile" size="40"
value="<?php echo $this->escape($this->user->get( 'mobile' ));?>" 
maxlength="50" /> *
</td>
</tr>