Hello guys,
Its really helpful for integration Paypal in PHP to verify card details.
To integrate it, first you have to download the PHP-Paypal SDK, below is the direct link
https://github.com/paypal/PayPal-PHP-SDK/releases

// 1. Autoload the SDK Package. This will include all the files and classes to your autoloader

require __DIR__  . '/PayPal-PHP-SDK/autoload.php';

// 2. Provide your Secret Key. Replace the given one with your app clientId, and Secret
// https://developer.paypal.com/webapps/developer/applications/myapps

$apiContext = new \PayPal\Rest\ApiContext(
    new \PayPal\Auth\OAuthTokenCredential(
        'AVv47dfPLzgZR4AJqOM4ch60p5vkJDekn09o9QaFp123vl7Dl96Tcz-RQJRJ83m1gIF12Uve2gOxqGz6',     // ClientID
        'EJfrUYfyf8yoXfeqyswaMmyP54exKT5L2jjhJOjJHbRkmR4-TdPBvHzOkydy8HKhTLpQNMThTp5HVL1f'      // ClientSecret
    )
);

// 3. Lets try to save a credit card to Vault using Vault API mentioned here
// https://developer.paypal.com/webapps/developer/docs/api/#store-a-credit-card

$creditCard = new \PayPal\Api\CreditCard();
$creditCard->setType("visa")
    ->setNumber("4417119669820331")
    ->setExpireMonth("11")
    ->setExpireYear("2019")
    ->setCvv2("012")
    ->setFirstName("Joe")
    ->setLastName("Shopper");

// 4. Make a Create Call and Print the Card

try {
    $creditCard->create($apiContext);
    echo $creditCard;
}
catch (\PayPal\Exception\PayPalConnectionException $ex) {
    // This will print the detailed information on the exception. 
    //REALLY HELPFUL FOR DEBUGGING

    echo $ex->getData();
}