我想在这里弄清楚几件事:
- 如何为具有指向下一个节点的指针的节点类编写递增运算符?
如何为如下类实现迭代器?
#include <iostream> #include <vector> using namespace std; template <typename T> class Node { public: Node(int i=0):val(i) {} Node*& operator++(int i=0) {return next;}; T val; Node *next; }; //================================================ int main() { Node<int> *head, *tmp1, *tmp2; tmp1 = new Node<int>(0); head = tmp1; for (int i=1; i<10; ++i) { tmp2 = new Node<int>(i); tmp1->next = tmp2; tmp1 = tmp2; } while (head != NULL) { cout << head->val << " '"; head = head->operator++(0); //How do I make it work with ++head;? } }
这不是演示运算符重载或迭代器的好例子。
最佳答案
您没有为 Node 类实现 operator++
;你为迭代器实现它。迭代器类应该是一个单独的类。
请不要通过假设破坏您的模板(因为 val
是一个 T
,您的构造函数应该接受一个 T
,不是 int
)。另外,不要像那样忽略 operator++ 的 int
参数:它是一个虚拟变量,用于区分预增量实现和后增量实现。
template <typename T>
struct Node {
T val;
Node *next;
Node(const T& t = T()) : val(t) {}
};
template <typename T>
struct node_iter {
Node<T>* current;
node_iter(Node<T>* current): current(current) {}
const node_iter& operator++() { current = current->next; return *this; }
node_iter operator++(int) {
node_iter result = *this; ++(*this); return result;
}
T& operator*() { return current->val; }
};
int main() {
// We make an array of nodes, and link them together - no point in
// dynamic allocation for such a simple example.
Node<int> nodes[10];
for (int i = 0; i < 10; ++i) {
nodes[i] = Node<int>(i);
nodes[i].next = (i == 9) ? nodes + i + 1 : 0;
}
// we supply a pointer to the first element of the array
node_iter<int> test(nodes);
// and then iterate:
while (test.current) {
cout << *test++ << " ";
}
// Exercise: try linking the nodes in reverse order. Therefore, we create
// 'test' with a pointer to the last element of the array, rather than
// the first. However, we will not need to change the while loop, because
// of how the operator overload works.
// Exercise: try writing that last while loop as a for loop. Do not use
// any information about the number of nodes.
}
距离提供适当的数据封装、内存管理等还有很长很长的路要走。制作一个适当的链表类并不容易。这就是为什么标准库提供了一个。不要重新发明轮子。
关于c++ - 增量运算符/迭代器实现,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/4329677/