How to add php in views?
Yes, it is possible.

If you want to use PHP in views header, you can go to configure header, select "Global: Text area" and have to change text format to PHP code; you have to first install the PHP filter module.

If you want to use PHP in view fields, you can use the Computed field module.

If you want to use PHP in a view itself, you have to customize your views and then you can easily add PHP code to it.