How to get customer credit card number based on Expiry date using x++ code

Get customer credit card number based on Expiry date validation 

public static RefRecId getCreditCardOCP(CustAccount    _custAccount)

{

    CreditCardCust custCreditCard;

    select firstOnly RecId,ExpiryDate from custCreditCard

            where custCreditCard.CustAccount == _custAccount;

    if(custCreditCard.ExpiryDate && CreditCard::checkExpireDate(custCreditCard.ExpiryDate))

    {

        return custCreditCard.RecId;

    }

    return 0;

}