.NET 3.x新特性之Lambda表达式

1 public class Person 
2 {
3   public string Name { get; set; }
4   public string NickName { get; set; }
5   public int Age { get; set; }
6 }

1 List<Person> people = new List<Person>
2    {
3      new Person{Name="小兵",NickName="网魂小兵",Age=23},
4      new Person{Name="青青",NickName="QQing",Age=22}
5    };
6      //取得people中Age为23的Person实例。
7      IEnumerable<Person> results = people.Where(p => p.Age == 23);
8      //计算people中的平均岁数。
9      int perAge = people.Average(p => p.Age);

1  List<Person> people = new List<Person>
2    {
3     new Person{Name="小兵",NickName="网魂小兵",Age=23},
4     new Person{Name="青青",NickName="QQing",Age=22}
5    };
6 
7    IEnumerable<Person> results = people.Where(delegate(Person p)
    { return p.Age == 23; });
8 
9    int perAge = people.Sum(delegate(Person p) { return p.Age; });

1 public static IEnumerable<TSource> Where<TSource>(
2 this IEnumerable<TSource> source, Func<TSource, bool> predicate);
3 public static IEnumerable<TSource> Where<TSource>( 
4 this IEnumerable<TSource> source, Func<TSource, int, bool> predicate);

1 public static IEnumerable<TSource> Where<TSource>(this IEnumerable<TSource> source,
2  Func<TSource, bool> predicate) 
3         {
4             foreach (TSource s in source) 
5             {
6                 if (predicate(s)) 
7                 {
8                     yield return s;
9                 }
10             }
11         }