c# - 理解字典，使用c#向字典添加新值

Question

如果我有 Customer 对象，它有 Payment 属性，它是自定义枚举类型和十进制值的字典，如

Customer.cs
public enum CustomerPayingMode
{
   CreditCard = 1,
   VirtualCoins = 2, 
   PayPal = 3
}
public Dictionary<CustomerPayingMode, decimal> Payment;

在客户端代码中，我在向字典添加值时遇到问题，像这样尝试

Customer cust = new Customer();
cust.Payment = new Dictionary<CustomerPayingMode,decimal>()
                      .Add(CustomerPayingMode.CreditCard, 1M);

Answer 1

Add()方法不返回可以分配给 cust.Payment 的值，您需要创建字典然后调用创建的 Dictionary 对象的 Add() 方法:

Customer cust = new Customer();
cust.Payment = new Dictionary<CustomerPayingMode,decimal>();
cust.Payment.Add(CustomerPayingMode.CreditCard, 1M);