C++ customized iterator for C-style array

std:: algorithms provides a nice zero-cost high level abstraction. It’s typically used together with std:: containers. However on embedded systems, std:: containers are two heavy to use as most of them requires dynamic allocation and flats the binary size.

Can std:: algorithm works on plain C-style array?

Yes! std:: algorithm is very generic. It works with almost any containers as long as the container can be visited with an iterator. So the question becomes, how to make a customized iterator for C-style array?

An iterator can be defined by inheriting from

std::iterator<std::input_iterator_tag, T>

and overrides ++,==, !=, * operators:

template <typename T>
class ForwardIterator : public std::iterator<std::input_iterator_tag, T> {
public:
explicit ForwardIterator(T* p) : p_(p){};
ForwardIterator& operator++() {
p_++;
return *this;
};
bool operator==(ForwardIterator other) const { return p_ == other.p_; }
bool operator!=(ForwardIterator other) const { return p_ != other.p_; }
T operator*() const { return *p_; }
private:
T* p_;
};

Then you can use it as usual:

int data[] = {1, 2, 3};
IntArray a(3, data);
auto iter = std::find(a.begin(), a.end(), 1);