lambda modern C++

Lambda expressions (since C++11)

Syntax

[ captures ] <tparams>(optional)(c++20) ( params ) specifiers(optional) exception attr -> ret { body }	(1)
[ captures ] ( params ) -> ret { body }	(2)
[ captures ] ( params ) { body }	(3)
[ captures ] { body }	(4)

上代码：

 // lambdaprj.cpp : Defines the entry point for the console application.
 //

 #include "stdafx.h"
 #include<algorithm>
 #include<vector>
 #include<iostream>
 #include<functional>
 using namespace std;

 /*
 *    []()->{};
 *    [ capture list] ( params list) mutable exception attribute -> ret { body }
 */
 int main()
 {
     auto sayHelloWorld = []() {
         cout << "hello world" << endl;
     };
     sayHelloWorld();
     auto add_ = [](int a,int b)->int {
         return a + b;
     };
     cout<< add_(, )<<endl;

     int i = ;//read only
     auto add_with_i = [i](int a, int b)->int {
         return a + b + i;
     };
     cout << add_with_i(,)<<endl;
     //

     int j = ;
     auto add_with_j_c = [&j](int a, int b)-> int{
         j = ;
         return a + b + j;
     };
     cout << add_with_j_c(, ) << " j:" << j << endl;
     //

     vector<int> arr = { ,,,, };
     int total = ;
     for_each(begin(arr), end(arr),
         [&](int x)->int{
         return total += x;
     });
     cout << "total:" << total << endl;
     //
     vector<int> sort_arr = { ,-,,,,,, };
     cout << "unsort : ";
     for_each(begin(sort_arr),end(sort_arr),
         [](int x) {
         cout << x << " "; });
     cout << endl;
     sort(begin(sort_arr),end(sort_arr),
         [](int a, int b)->bool {
         return abs(a) < abs(b); });
     cout << "sort   : ";
     for_each(begin(sort_arr), end(sort_arr),
         [](int x) {
         cout << x << " "; });
     cout << endl;
     //

     auto func = [](function<void()> f) {
         f();
     };
     int x = ;
     auto func_add = [&]() {
         x++;
     };
     func(func_add);
     cout << "x:" << x << endl;
     getchar();
     return ;
 }

参考学习：

1、https://www.youtube.com/watch?v=uk0Ytomv0wY

2、http://en.cppreference.com/w/cpp/language/lambda