// This file, part of a series, show why functors are so cool,
// because they can maintain state information:
// - from the constructor
// - from call-to-call
//
// Instead of hard-coding “2”, so that the code removes every 2nd vowel,
// the functor has a data member “period”, initialized in the ctor.

#include <iostream>
#include <set>
#include <algorithm>
#include <iterator>
#include <cstring>

using namespace std;

class IsVowel {
    const int period;		// Hey, const!
    int count;
  public:
    IsVowel(int how_often) : period(how_often), count(0) {}
    bool operator()(char c) {
	    return string("aeiouyAEIOUY").find(c) != string::npos
		&& (++count % period) == 0;
    }
};


int main() {
    char name[] = "James Tiberius Kirk";

    remove_copy_if(name, name+strlen(name),
	 ostream_iterator<char>(cout), IsVowel(2));
    cout << '\n';
}