<?php
// Exit if accessed directly
if (!defined('ABSPATH')) {
    exit;
}

// Track Post Views
function ajcps_set_post_views($postID) {
    $count = get_post_meta($postID, 'post_views_count', true);
    $count = $count ? intval($count) + 1 : 1;
    update_post_meta($postID, 'post_views_count', $count);
}
add_action('wp_head', function() {
    if (is_single()) {
        global $post;
        if ($post) {
            ajcps_set_post_views($post->ID);
        }
    }
});