collection_codes_int.cpp

// https://en.cppreference.com/w/cpp/language/range-for
// range based for
#include <iostream>
#include <vector>

int main() {
  std::vector<int> v = {0, 1, 2, 3, 4, 5};

  for (const int &i : v) // access by const reference
    std::cout << i << ' ';
  std::cout << '\n';

  for (auto i : v) // access by value, the type of i is int
    std::cout << i << ' ';
  std::cout << '\n';

  for (auto &&i : v) // access by forwarding reference, the type of i is int&
    std::cout << i << ' ';
  std::cout << '\n';

  const auto &cv = v;

  for (auto &&i : cv) // access by f-d reference, the type of i is const int&
    std::cout << i << ' ';
  std::cout << '\n';

  for (int n : {0, 1, 2, 3, 4, 5}) // the initializer may be a braced-init-list
    std::cout << n << ' ';
  std::cout << '\n';

  int a[] = {0, 1, 2, 3, 4, 5};
  for (int n : a) // the initializer may be an array
    std::cout << n << ' ';
  std::cout << '\n';

  for (int n : a)
    std::cout << 1 << ' '; // the loop variable need not be used
  std::cout << '\n';
}

// https://www.acodersjourney.com/top-10-dumb-mistakes-avoid-c-11-smart-pointers/

// http://pages.cs.wisc.edu/~driscoll/typename.html