使用new关键字实例化一个委托。创建委托时,传递给新表达式的参数与方法调用类似,但不包含方法的参数。
例如-
public delegate void printString(string s); printString ps1 = new printString(WriteToScreen);
您还可以使用匿名方法实例化委托-
//declare delegate void Del(string str); Del d = delegate(string name) { Console.WriteLine("Notification received for: {0}", name); };
让我们看一个声明并实例化委托的示例-
using System; delegate int NumberChanger(int n); namespace DelegateAppl { class TestDelegate { static int num = 10; public static int AddNum(int p) { num += p; return num; } public static int MultNum(int q) { num *= q; return num; } public static int getNum() { return num; } static void Main(string[] args) { //创建委托实例 NumberChanger nc1 = new NumberChanger(AddNum); NumberChanger nc2 = new NumberChanger(MultNum); //使用委托对象调用方法 nc1(25); Console.WriteLine("Value of Num: {0}", getNum()); nc2(5); Console.WriteLine("Value of Num: {0}", getNum()); Console.ReadKey(); } } }
输出结果
Value of Num: 35 Value of Num: 175