anonymous function and this code example

Example: anonymous functor

1 int function (int a) {
 2   return a + 3;
 3 }
 4 
 5 class Functor {
 6   public:
 7     int operator()(int a) {
 8       return a + 3;
 9     }
10 };
11 
12 int main() {
13   auto lambda = [] (int a) { return a + 3; };
14 
15   Functor functor;
16 
17   volatile int y1 = function(5);
18   volatile int y2 = functor(5);
19   volatile int y3 = lambda(5);
20 
21   return 0;
22 }