public bool AddCard(string cardnumber)
{
if (IsValidCardnumber(cardnumber))
{
Cardnumbers.Add(cardnumber);
return(true);
}
return(false);
}
public Customer(string name, bool temporary, decimal balance, string cardnumber)
: this(name, temporary, balance)
{
if (!IsValidCardnumber(cardnumber))
{
throw new ArgumentException("cardnumber");
}
Cardnumbers.Add(cardnumber);
}
