main03.cpp

#include <iostream>
#include <vector>

int main () {
    std::vector<int> counters = {10, 20, 30};

    // need mutable as lambda by default is a const expression
    auto passByValueLambda = [=] () mutable {
        std::cout << "Hello, lambda by value" << std::endl;
        // modifying the copy - original vector is not influenced
        counters.push_back(1000);
    };

    passByValueLambda();

    std::for_each(counters.begin(), counters.end(),
                  [](int a) { std::cout << a << std::endl;});

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

    // reinitialize the vector gain
    counters = {10, 20, 30};
    auto passByReferenceLambda = [&] () {
        std::cout << "Hello, lambda by reference" << std::endl;
        counters.push_back(1000);
    };

    passByReferenceLambda();

    std::for_each(counters.begin(), counters.end(),
                  [](int a) { std::cout << a << std::endl;});
}