How to replace add to cart button in WP?

Question

WordPress

There is a button for the product - Add to cart - that 's when you press it, it adds the product to the cart). And you need this button to change if the product is added to the cart. The client added the product the button has changed for example - the button says - the product has been added.
Here is the code

<a rel="nofollow" href="/?add-to-cart=<?php echo $post->ID; ?>" data-quantity="1" data-productid="<?php echo $post->ID; ?>" data-productsku="" class="button producttypesimple <?php echo (getpostmeta($post->ID, 'managestock', true) == 'yes' && (getpostmeta($post->ID, 'stock', true) - $productquantity) > 0) ? 'add addtocartbutton' : 'addtocartfalse'; ?> ajaxaddtocart added"><?php echo (getpostmeta($post->ID, 'managestock', true) == 'yes' && (getpostmeta($post->ID, 'stock', true) - $product_quantity) > 0) ? '' : 'Нет в наличии.'; ?></a>

I do not understand where to add. Who can advise?

Answer 1

I don't understand where to add your code.
Well, even I guess that all the magic happens in the code above.