Closure in C++11

closure.cpp

#include <iostream>
#include <functional>
using namespace std;

function<void()> closure() {
    int a = 0;
    auto func = [a]() mutable {
        a += 1;
        cout << a << endl;
    };
    return func;
}

int main() {
    auto f = closure();
    f(); //1
    f(); //2
    f(); //3
    f(); //4
    return 0;
}