functor example

functor_example.cc

// Source: http://stackoverflow.com/questions/356950/c-functors-and-their-uses
#include <assert.h>
#include <vector>
#include <algorithm>
#include <iostream>

struct add_x {
  add_x(int x) : x(x) {}
  int operator()(int y) {return x+y;}
  private: int x;
};

int main()
{
  add_x add1(1);
  int i = add1(1);
  assert(i == 2);

  int myints[] = {1, 2, 3, 4, 5};
  std::vector<int> in(myints, myints + sizeof(myints) / sizeof(int));
  std::vector<int> out (in);
  std::transform(in.begin(), in.end(), out.begin(), add_x(10));
  for (int i = 0; i < in.size(); ++i) {
    //assert(out[i] == in[i] + 1);
    std::cout << out.at(i) << std::endl;
  }
  return 0;
}