COBOL-style contraol breaks in C++

ctlbr.cc

#include <functional>
#include <stdlib.h>
#include <iostream>
#include <vector>



template <class T>
class breaker {
        public:
        breaker(std::vector<T>& cont, std::function<bool (T,T)> same_grp)
        : c_cont (cont), idx (-1), c_same_grp (same_grp)
        { num = cont.size();}
        bool more() {  idx++; return idx < num; }
        T get() { return c_cont[idx]; }
        bool first() { return idx == 0 || ! c_same_grp(c_cont[idx-1], c_cont[idx]); }
        bool last() { return idx +1 == num | !c_same_grp(c_cont[idx],c_cont[idx+1]);}
        int idx;
        int num;
        std::function<bool (T, T)> c_same_grp;

        private:
        std::vector<T>& c_cont;


};

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

        auto higher = [](int a, int b) { return a <= b;};
        breaker<int> brk(v, higher);
        int total;
        while(brk.more()) {
                if(brk.first()) { total = 0; std::cout << "Starting group\n"; }
                std::cout << brk.get() << "\n" ;
                total += brk.get();
                if(brk.last()) { std::cout << "Group total: " << total << "\n\n";}
        }
        return EXIT_SUCCESS;
}

It processes input, breaking it into groups. The grouping function is passed in as function: higher in this case. It might typically look up a field, but in this case, it assumes that numbers in ascending order are part of a group, and starts a new group if it encounter a lower number.

Output is:

Starting group
1
3
5
Group total: 9

Starting group
2
4
Group total: 6

Starting group
3
Group total: 3