C # delegate, anonymous function, lambda evolution

Delegate Keyword: delegate

A delegate is a method that passes as a parameter.

Declare a delegate first: two parameters, return bool type

Delegate BOOL MyDelegate (object obj1,object obj2);

The method that the delegate corresponds to:

    Static BOOL Comparenums (object obj1,object  obj2)        {            return (int) obj1 > ( int ) obj2;        }

method to get the maximum value:

Static Object Getmax (object[] objs,mydelegate mydelegate)        {            object max = objs[0];             foreach (var in objs)            {                if  (comparenums (item, max))                {                    = item;                }            }             return max;       }

Call Method:

        Static void Main (string[] args)        {            object[] nums = {1,2,3,  4,5,0  };             New mydelegate (comparenums);             object max = Getmax (nums, Mydel);            Console.WriteLine (max);            Console.readkey ();        }

======== because the method to get the maximum value is used only once, you can use the anonymous method instead, which is more concise =======

        Static voidMain (string[] args) {            Object[] Nums = {1,2,3,4,5,0 }; MyDelegate Mydel=Delegate(ObjectObj1,ObjectOBJ2) {return(int) Obj1 > (int) Obj2;            }; ObjectMax =Getmax (Nums, Mydel);            Console.WriteLine (max);        Console.readkey (); }

================= because the system comes with action and func two kinds of delegates, there is no need to customize the delegate =================

Action delegate return value is void

Func has a return value

The Get maximum value method is modified to:

        Static ObjectGetmax (Object[] objs,func<Object,Object,BOOL>func) {            Objectmax = objs[0]; foreach(varIteminchObjs) {                if(Comparenums (item, max)) {Max=item; }            }            returnMax; }

Method calls are modified to:

        Static voidMain (string[] args) {            Object[] Nums = {1,2,3,4,5,0 }; Func<Object,Object,BOOL> func=Delegate(ObjectObj1,ObjectOBJ2) {return(int) Obj1 > (int) Obj2;            }; ObjectMax =Getmax (Nums, func);            Console.WriteLine (max);        Console.readkey (); }

================= using lambda for simplified ====================

        Static voidMain (string[] args) {            Object[] Nums = {1,2,3,4,5,0 }; Func<Object,Object,BOOL> func = (obj1, obj2) = {return(int) Obj1 > (int) Obj2;            }; ObjectMax =Getmax (Nums, func);            Console.WriteLine (max);        Console.readkey (); }

C # delegate, anonymous function, lambda evolution