【转】override（C# 参考）

示例 

此示例定义了一个名为 Employee 的基类，和一个名为 SalesEmployee 的派生类。SalesEmployee 类包括一个额外的属性 salesbonus，并重写方法 CalculatePay 以便将该属性考虑在内。

using System;
class TestOverride
{
    public class Employee
    {
        public string name;

        // Basepay is defined as protected, so that it may be 
        // accessed only by this class and derrived classes.
        protected decimal basepay;

        // Constructor to set the name and basepay values.
        public Employee(string name, decimal basepay)
        {
            this.name = name;
            this.basepay = basepay;
        }

        // Declared virtual so it can be overridden.
        public virtual decimal CalculatePay()
        {
            return basepay;
        }
    }

    // Derive a new class from Employee.
    public class SalesEmployee : Employee
    {
        // New field that will affect the base pay.
        private decimal salesbonus;

        // The constructor calls the base-class version, and
        // initializes the salesbonus field.
        public SalesEmployee(string name, decimal basepay, 
                  decimal salesbonus) : base(name, basepay)
        {
            this.salesbonus = salesbonus;
        }

        // Override the CalculatePay method 
        // to take bonus into account.
        public override decimal CalculatePay()
        {
            return basepay + salesbonus;
        }
    }

    static void Main()
    {
        // Create some new employees.
        SalesEmployee employee1 = new SalesEmployee("Alice", 
                      1000, 500);
        Employee employee2 = new Employee("Bob", 1200);

        Console.WriteLine("Employee " + employee1.name + 
                  " earned: " + employee1.CalculatePay());
        Console.WriteLine("Employee " + employee2.name + 
                  " earned: " + employee2.CalculatePay());
    }
}

输出

Employee Alice earned: 1500

Employee Bob earned: 1200