form validation for NOT matches

[eluser]blorriman[/eluser]

Code:

<div id="signup_form" class="span-10">
    <fieldset>
        <legend>Create New Account</legend>
    &lt;?php
        echo form_open('login/create_member');
        $data = array(
              'name'        => 'first_name',
              'id'          => 'first_name',
              'placeholder' => 'First Name',
              'value'       => set_value('first_name','set first name')
            );

        echo form_input($data). '<br>';
//        echo form_input('first_name', set_value('first_name', 'enter first name')). '<br>';
        echo form_input('last_name', set_value('last_name', 'last name')). '<br>';
        echo form_input('email_address', set_value('email_address', 'email address')). '<br>';
    ?&gt;
    </fieldset>
</div>
<div id="signup_form" class="span-10 push-2">
    <fieldset>
        <legend>Login Information</legend>
        &lt;?php
            echo form_input('username', set_value('username', 'username')). '<br>';
            echo form_input('password', set_value('password','password')). '<br>';
            echo form_input('password2', set_value('password2','confirm password')). '<br>';
            echo form_submit('submit', 'create account'). '<br>';
        ?&gt;

        &lt;?= validation_errors('<p class="error">');?&gt;
    </fieldset>
</div>