1 #include <iostream>
2 #include <array>
3 using namespace std;
4
5 //解决函数怀孕现象
6 //[](){}
7 //[] =引用,只读 =mutable读原本改副本 &读写原本 //&a,b a可读写,b只能读
8 //() 参数,int a,int b
9 //{}语句
10 void main()
11 {
12 //lambda表达式
13 auto fun1 = [] {cout << "hello" << endl; cout << "hello2" << endl; };//函数指针
14 fun1();//括号起到调用的作用
15
16 //[](参数列表){执行逻辑}
17 auto fun2 = [](char *str) {cout << str << endl; };
18 fun2("hello3");
19
20 //lambda带参函数
21 auto fun3 = [](int a, int b) {return a + b; };
22 cout << fun3(10, 19) << endl;
23
24 //->用在(){}之间,用于确定返回值类型
25 auto fun4 = [](int a, int b)->double {return a + b; };
26 cout << fun4(10, 19) << endl;
27
28 //decltype解决类型自动推理
29 auto fun5 = [](int a, int b)->decltype(a+b) {return a + b; };
30 cout << fun5(10, 19) << endl;
31
32 int num1 = 20;
33 int num2 = 33;
34 //=可以使用外部变量,只能读不能写
35 auto fun6 = [=](){cout << num1 << num2 << endl; };
36 fun6();
37
38 //&可以使用外部变量,读写(对原数据的操作)
39 auto fun7 = [&](){num1 = 1; cout << num1 << num2 << endl; };
40 fun7();
41
42 //mutable可以使用外部变量,读写(副本机制,不对原数据进行改变)
43 auto fun8 = [=]()mutable{num1 = 1; cout << num1 << num2 << endl; };
44 fun8();
45
46 //指定可读写的元素 num1可读可写,num2只能读
47 auto fun9 = [&num1, num2]() {num1 = 30; cout << num2 << endl; };
48 fun9();
49
50 //mutable可读可写但作用的是副本
51 auto fun10 = [num1, num2]() mutable{num1 = 30; cout << num2 << endl; };
52 fun10();
53
54 //lambda与auto
55 auto fun11 = [](auto a, auto b)->decltype(a+b){return a + b; };
56 cout << fun11(1,3.9) << endl;
57
58 //内嵌调用lambda
59 array<int, 10> myarray{1, 2, 3, 4, 5, 6, 7, 8, 9, 0};
60 for_each(myarray.begin(), myarray.end(), [](int &num) {num += 1; cout << num << endl; });
61 cin.get();
62 }
