title: Paypal credit card validation
body: <p>I want to check that the credit card number provided by customer to my site is valid or not for further transaction. for that i wand to only verify taht the CC no is valid or not by Paypal. 
  A method for that can be with paypal api
  step 1: DoDirectPayment with PAYMENTACTION=Authorization for amt of $1, then
  step 2: DoVoid that request</p>
  
  <p>Does any one can tell me
  is any amount is charged by paypal for doing tis stuff?
  or any other better way you know?</p>
  
  <p>My site is in PHP..</p>