// Demonstrating use of count_if and find_if algorithms with list


#include <list.h>
#include <algo.h>
#include <assert.h>

void show_int (int x)
{
  cout << x << " ";
}

// sample PREDICATE functions -- take a parameter of same
// type as the container, and pass back boolean if condition is true

// Predicate works as a "filter" or "test" that can be applied on 
// STL containers with considerable convenience

bool greater_than_50 (int x)
{
  return x > 50 ? true : false;
}

bool even_p (int a)
{
  return ! (a % 2);
}

int main()
{
  cout << "Demonstrating count_if and find_if with lists." << endl;

  list<int> list2;

  // populating the list using "push_back"
  list2.push_back(89);
  list2.push_back(99);
  list2.push_back(89);
  list2.push_back(69);
  list2.push_back(59);
  list2.push_back(89);
  list2.push_back(89);
  list2.push_back(49);

  cout << "LIST2 Elements: " << endl;
  for_each(list2.begin(), list2.end(), show_int);
  cout << endl;

  // is there are a number in the list that satisfies a
  // particular predicate (or test)

  list<int>::iterator ip;

  ip = find_if(list2.begin(), list2.end(), greater_than_50);
  if (ip !=list2.end())
    cout << "The first number greater than 50 is: " << *ip << endl;
  else
    cout << "No number greater than 50 in list2" << endl;

  cout << "Number of items greater than 50 in list2: " 
       << count_if(list2.begin(), list2.end(), greater_than_50)
	 << endl;

  cout << "Number of even numbers in list2: " 
       << count_if(list2.begin(), list2.end(), even_p)
	 << endl;


}