Insert class if true

Question

How do I insert a class with php if something is true? Here's my best guess so far:

<div class="<?php
  if($this->step==2){
    somehow set the name of the class
  } ?>">

Answer 1

You're close; what you can do is echo the class with PHP.

<!-- Either try this... -->
<div class="<?php if($this->step === 2) { echo 'twostep'; } ?>"></div>

<!-- ...or this -->
<div class="<?=$this->step === 2 ? 'twostep' : 'notwostep'?>"></div>