You posted this question yesterday, and got a sensible answer.
However, it seems from your replies to that answer that you do not want to do any paypal payments, but set up your own system for making or taking credit card payments. Is this the case?
If so, then:
Never, ever, accept code from a insecure website to handle anything to do with real money.
You do not know who is giving you the code, you do not know what it does, you do not know that it places the monies correctly into the appropriate account, without passing the details to any third parties.
Only get such code from reputable card transaction service companies - the scope for fraud otherwise is far to large. And remember, you personally could be liable for any monies lost if your action seem to be negligent - which getting your code from a public forum would most certainly be!
"yes i want to develop my own system for making or taking credit card payments.can you provide me with code."
"i am gona use it for my internal project and for knowlegde"
It doesn't matter - you must not rely now, or in the future, on code which cannot be trusted. And when money is concerned, no code from a public website can be trusted!
Instead, why not actually use Paypal - if I remember correctly, they have a "Sandbox" mode which allows you to run a full system, with fully working payments, except no real money, or real accounts are ever affected
1. Most CC validation companies will do the same, I believe.
A Sandbox version would also have the advantage of not costing you transaction fees every time you test your software...
1 They do: http://www.google.co.uk/search?sourceid=chrome&ie=UTF-8&q=paypal+sandbox[^]