How capture work with lambda functions

lambdas.cpp

#include <iostream>

int main(void)
{
    int a = 1001;
    long double b = 3.1415926;
    char c = 'A';
    std::string d = "I like C";

    std::cout << "a: " << a << std::endl;
    std::cout << "b: " << b << std::endl;
    std::cout << "c: " << c << std::endl;
    std::cout << "d: " << d << std::endl;

    auto f = [&a, &b, &c, d]()
    {
        a++;
        b *= 2;
        c++;
        //d += "++";
    };

    f();

    std::cout << "------------------" << std::endl;

    std::cout << "a: " << a << std::endl;
    std::cout << "b: " << b << std::endl;
    std::cout << "c: " << c << std::endl;
    std::cout << "d: " << d << std::endl;

    return 0;
}