Step 2 of 5

Writing an iterator class

When the data isn't contiguous (a linked list, a tree, a file), you write an iterator class. For a forward iterator you need:

• operator* to get the current element
• operator++ (prefix) to advance, returning *this
• operator== to compare (C++20 generates != for you)

class Iter {
public:
    explicit Iter(Node* n) : node_(n) {}
    int& operator*() const { return node_->value; }
    Iter& operator++() { node_ = node_->next; return *this; }
    bool operator==(const Iter& o) const { return node_ == o.node_; }
private:
    Node* node_;
};

end() is simply an iterator holding nullptr, the position one past the last node.

Your turn: finish the Iterator inside IntList and add begin() and end().

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