An example showing how to use some functional constructs in C++

functional.cpp

#include <iostream>
#include <string>
#include <vector>

int main()
{
  // Enter lambda functions..
  auto sum = [] (int x, int y) {
    std::cout << "Hello, side-effects!" << std::endl;
    return x + y;
  };
  std::cout << "1 + 2 = " << sum(1, 2) << std::endl;

  // Accessing outer scope from lambdas
  std::vector<int> vec = {1, 2, 3, 4, 5};
  ([&vec] (int i) { vec.push_back(i); })(42);

  // Dump the vector to see that its content has changed:
  for (auto el : vec)
    std::cout << el << ' ';
  std::cout << std::endl;

  // any_of, all_of, find_if
  auto is_any_even = std::any_of(vec.begin(), vec.end(), [] (int el) {return el % 2 == 0;});
  auto all_less_than_ten = std::all_of(vec.begin(), vec.end(), [] (int el) {return el < 10;});
  auto first_non_even = std::find_if(vec.begin(), vec.end(), [] (int el) {return el % 2 != 0;});
  std::cout << "First non_even is " << *first_non_even << std::endl;
}