Core Implementation of linq

Query operators and extension methods

The query operator is an important facility of linq, which uses extended methods to define query operations;

For example, the where OPERATOR:

Initial linq expression

Core Implementation of Linq

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

Initial linq expression

 1 class app 2 { 3       static void main() 4       { 5             string[] names={"Burke","Connor","Frank","Everett","Albert","George","Harris","David"}; 6  7             IEnumerable<string> query=from s in names 8                                                        where s.Length==5 9                                                        orderby s10                                                        select s.ToUpper();11 12 13               foreach(string item in query)14               {15                      Console.WriteLine(item);16                }17 18       }19 }

Lambda expressions, similar to the following delegate to a common method to call the Extension Method

1 IEnumerable<string> query=Enumerable.Where(names,s=>s.Length<6);

C # Allow this method to call the Extension Method

1 IEnumerable<string> query=names.Where(s=>s.Length>6);