自定义数据类型，操作符重载实例[C#]

/// <summary>
/// 货币类型基类
/// </summary>
public class Currency
{
//货币实际数值
public decimal price { get; set; }
public Currency(decimal value)
{
price = value;
}
//重载ToString方法
public override string ToString()
{
return price.ToString();
}
}
public class USD : Currency
{
//继承基类构造函数
public USD(decimal value) : base(value) { }
/// <summary>
/// 此方法重载＝号，可以直接使用＝号赋值
/// </summary>
/// <param name="value"></param>
/// <returns>返回ＵＳＤ货币类型</returns>
public static implicit operator USD(decimal value)
{
return new USD(value);
}
/// <summary>
/// 重载+号，同货币可以相加
/// </summary>
/// <param name="usd"></param>
/// <param name="other"></param>
/// <returns>返回ＵＳＤ货币类型</returns>
public static USD operator +(USD usd, USD other)
{
return new USD(usd.price + other.price);
}
/// <summary>
/// 重载-号，同货币可以相减
/// </summary>
/// <param name="usd"></param>
/// <param name="other"></param>
/// <returns>返回ＵＳＤ货币类型</returns>
public static USD operator -(USD usd, USD other)
{
return new USD(usd.price - other.price);
}
/// <summary>
/// 重载*号，可以同decimal类型相乘
/// </summary>
/// <param name="usd"></param>
/// <param name="other"></param>
/// <returns>返回ＵＳＤ货币类型</returns>
public static USD operator *(USD usd,decimal other)
{
return new USD(usd.price * other);
}
/// <summary>
/// 重载/号，可以同decimal类型相除
/// </summary>
/// <param name="usd"></param>
/// <param name="other"></param>
/// <returns>返回ＵＳＤ货币类型</returns>
public static USD operator /(USD usd, decimal other)
{
return new USD(usd.price * other);
}
}