代码是C#红皮书第六版上看书的
代码 public interface IAccount { decimal Balance { get ; } string Name { get ; } } public class Account : IAccount { private string name; public string Name { get { return name; } } private decimal balance; public decimal Balance { get { return balance; } } public Account( string name, decimal balance) { this .name = name; this .balance = balance; } } public static class Algorithe { // 2个泛型委托 public delegate Y Action < T, Y > (T t, Y u); public delegate bool Predicate < T > (T input); // Where T : IAccount...泛型约束，因为方法里使用了该接口的属性 // 第一个参数：实现了IEnumerable<T>接口的类，以便Foreach // 第二三个参数，上面2个委托类型的方法 public static Y Acculateb < T, Y > (IEnumerable < T > col, Action < T, Y > action, Predicate < T > match) where T : IAccount { Y sum = default (Y); foreach (T input in col) { // 使用委托方法 if (match(input)) { // 使用委托方法 sum = action(input, sum); } } return sum; } } class Program { static void Main( string [] args) { List < Account > list = new List < Account > (); list.Add( new Account( " wht " , 1 )); list.Add( new Account( " my " , 2 )); // 2个委托参数都用Lamda表达式，很方便 decimal aa = Algorithe.Acculateb < Account, decimal > (list, (a, b) => a.Balance + b, f => f.Name == " wht " ); // 测试 Console.WriteLine(aa); Console.Read(); } }
转载于:https://www.cnblogs.com/renjuwht/archive/2010/01/09/1643175.html
