了解由函数指针到Lambda表达式的演化过程
Lambda表达式的这种简洁的语法并不是什么古老的秘法,因为它并不难以理解(难以理解的代码只有一个目的,那就是吓唬程序员)
1 #include "stdafx.h" 2 using namespace System; 3 4 typedef void(*FunctionPointer)(System::String ^str); 5 6 void HelloWorld(System::String ^str) 7 { 8 Console::WriteLine(str); 9 Console::ReadLine(); 10 } 11 12 int main(array<System::String ^> ^args) 13 { 14 FunctionPointer fp = HelloWorld; 15 fp("Hello World"); 16 return 0; 17 }
1 using System; 2 using System.Collections.Generic; 3 using System.Text; 4 5 namespace CharpFunctionPointer { 6 class Program { 7 8 delegate void FunctionPointer(string str); 9 10 static void Main(string[] args) { 11 FunctionPointer fp = HelloWorld; 12 fp("Hello World!"); 13 } 14 15 static void HelloWorld(string str) { 16 Console.WriteLine(str); 17 Console.ReadLine(); 18 } 19 } 20 21 }
1 using System; 2 using System.Collections.Generic; 3 using System.Text; 4 5 namespace CharpFunctionPointer { 6 class Program { 7 8 delegate void FunctionPointer(string str); 9 10 static void Main(string[] args) { 11 FunctionPointer fp = delegate (string s) { 12 Console.WriteLine(s); 13 Console.ReadLine(); 14 }; 15 fp("Hello World!"); 16 } 17 } 18 19 }
1 using System; 2 using System.Collections.Generic; 3 using System.Text; 4 5 namespace CharpFunctionPointer { 6 class Program { 7 8 delegate void FunctionPointer(string str); 9 10 static void Main(string[] args) { 11 FunctionPointer fp = 12 s => Console.WriteLine(s); 13 14 fp("Hello World!"); 15 Console.ReadLine(); 16 } 17 } 18 }
1 using System; 2 using System.Collections.Generic; 3 using System.Text; 4 5 namespace CharpFunctionPointer { 6 class Program { 7 8 static void Main(string[] args) { 9 Action<string> fp = s => Console.WriteLine(s); 10 11 fp("Hello World!"); 12 Console.ReadLine(); 13 } 14 } 15 }
Lambda表达式和闭包
1 using System; 2 using System.Collections.Generic; 3 using System.Text; 4 using System.Linq; 5 6 namespace LambdaClosure { 7 class Program { 8 9 static void Main(string[] args) { 10 UsesClosure(); 11 } 12 13 static void UsesClosure() { 14 string toFind = "ed"; 15 var words = new string[] { 16 "ended","friend","closed","potato" 17 }; 18 19 var matches = words.Select(s => s.Contains(toFind)); 20 foreach(var str in matches) { 21 Console.WriteLine(str); 22 } 23 Console.ReadLine(); 24 } 25 } 26 }
柯里化(Currying)
1 using System; 2 using System.Collections.Generic; 3 using System.Text; 4 using System.Linq; 5 6 namespace LambdaCurry { 7 class Program { 8 9 static void Main(string[] args) { 10 Func<int,int,int> longLambda = (x,y) => x + y; 11 Console.WriteLine(longLambda(3,4)); 12 13 //currying 14 Func<int,Func<int,int>> curry = x => y => x + y; 15 Console.WriteLine(curry(3)(4)); 16 17 Console.ReadLine(); 18 } 19 } 20 }