Check if WordPress post number is even or odd. And running some actions based on findings

WordPress odd or even.php

<?php
// First we need to set counter
$postnum = 1;

// Running WordPress loop to get all posts
if (have_posts()) :
	while (have_posts()) : the_post();
	
		// Time to check if post number is even or odd
    		if ($postnum&1) : ?>
    	
    			<!-- do some actions if number is odd -->
      			<div class='row'></div>
      	
      		<?php
      		endif;
      	
      		// Increase the counter
    		$postnum++;
    	endwhile;
endif; ?>