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ranges_example.cpp
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ranges_example.cpp
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#include <utility>
#include <iostream>
#include <vector>
#include <ranges>
#include <algorithm>
class fib_iterator {
int cur_ = 0;
int next_ = 1;
public:
using value_type = int;
using difference_type = int;
int operator*() const { return cur_; }
fib_iterator& operator++() {
cur_ = std::exchange(next_, cur_ + next_);
return *this;
}
fib_iterator operator++(int) {
auto oldval = *this;
++*this;
return oldval;
}
};
template <auto V> struct EndValue {
bool operator==(auto pos) const { return *pos == V; }
};
int main() {
fib_iterator fi;
for(int i = 0; i < 10; ++i, ++fi)
std::cout << *fi << ",";
std::cout << "\n";
fib_iterator fi2;
auto ci = std::counted_iterator{fi2, 10};
for(auto it = ci; it != std::default_sentinel; ++it) {
std::cout << *it << ",";
}
std::cout << "\n";
std::vector<int> v {1, 4, 2, 8, 16, 32, 64};
auto w = std::ranges::subrange(v.begin() + 1, EndValue<8>{});
std::ranges::common_view cv(w);
// std::sort(cv.begin(), cv.end());
fib_iterator fi3;
auto fv = std::ranges::subrange {fi3, std::unreachable_sentinel};
auto fib_tk = std::views::take(fv, 10);
for(auto item: fib_tk) {
std::cout << item << ",";
}
return 0;
}