Scenario  :  adding mutiple products to cart in magento which have quantity greater than zero value.
Solution :
1/ Create a button that send a request for adding multiple products to cart in magento.

2/Create a controller to handle it.It will extend Mage_Checkout_CartController

Let’s begin coding :

1/Create a button that send a request for adding multiple products to cart in magento.
Go to the the file : app/design/frontend/default/your-current-theme/catalog/product/list.phtml
Please notify the highlight code and put them in proper section.

2/Create a controller to handle it.It will extend Mage_Checkout_CartController
– Declare module : Create app/etc/modules/Yourcompany_Multiplecart.xml for registering new module in magento :

Create app/code/local/Yourcompany/Multiplecart/etc/config.xml

Create CartController.php : app/code/local/Yourcompany/Multiplecart/controllers/Checkout/CartController.php

Try to refresh your cache to see this changes. Happy coding!