C++ class实现单向循环链表(完整代码)

注意:
写Delete_all要稍微注意一下，先判断tail是否为空，只有不为空时才能拿某个指针指向其next域

代码如下:

#include <iostream>
using namespace std;
typedef int ElemType;
#define  NO 0class Node {friend class LinkList;public:Node(): next(NULL) {};private:ElemType data;Node *next;
};class LinkList {public:LinkList(): tail(NULL) {};~LinkList() {Delete_all();}void Init();void TailCreateList(int n);void HeadCreateList(int n);void PrintList();Node *Locate_i(int i);Node *Locate_e(ElemType e);ElemType Get(int i);bool Insert(ElemType e, int i);bool Delete(int i);void Delete_all();private:Node *tail;
};void LinkList::Init() {Delete_all();tail = NULL;
}void LinkList::TailCreateList(int n) {Node *s, *r, *p;Delete_all();p = new Node();p->next = NULL;r = p;for (int i = 1; i <= n; i++) {s = new Node();cin >> s->data;r->next = s;r = s;}r->next = p;tail = r;
}void LinkList::HeadCreateList(int n) {Node *p, *s;Delete_all();p = new Node();p->next = p;bool flag = true;for (int i = 1; i <= n; i++) {s = new Node();cin >> s->data;if (flag) {tail = s;flag = false;}s->next = p->next;p->next = s;}
}void LinkList::PrintList() {Node *p;p = tail->next->next;while (p != tail->next) {cout << p->data << " ";p = p->next;}cout << endl;
}Node *LinkList::Locate_i(int i) {if (i == 0)return tail;Node *p;p = tail->next->next;int j = 1;while ((p != tail->next) && (j < i)) {j++;p = p->next;}if (j == i)return p;else {cout << "position is not correct!!!" << endl;return NULL;}
}Node *LinkList::Locate_e(ElemType e) {Node *p;p = tail->next->next;while ((p != tail->next) && (p->data != e))p = p->next;if (p != tail->next)return p;else {cout << e << " is not exist!!!" << endl;return NULL;}
}ElemType LinkList::Get(int i) {Node *p;p = tail->next->next;int j = 1;while ((p != tail->next) && (j < i)) {j++;p = p->next;}if (j == i)return p->data;else {cout << "position is not correct!!!" << endl;return NO;}
}bool LinkList::Insert(ElemType e, int i) {Node *p, *s;p = Locate_i(i - 1);if (p != NULL) {s = new Node();s->data = e;s->next = p->next;p->next = s;if (tail->next == s)tail = s;return true;} else {cout << "position is not correct!!!" << endl;return false;}
}bool LinkList::Delete(int i) {Node *p, *q;p = Locate_i(i - 1);if (p != NULL) {q = p->next;if (q == tail)tail = p;p->next = q->next;delete q;return true;} else {cout << "position is not correct!!!" << endl;return false;}
}//注意!!! 先判断tail是否为空，只有不为空时才能拿某个指针指向其next域
void LinkList::Delete_all() {Node *p, *q;q = tail;//注意，这里要先判断tail是不是NULLif (q == NULL) {tail = NULL;return ;}p = tail->next;//只有tail不是NULL的时候，p才能指向tail->next，否则会出错。q->next = NULL;while (p != NULL) {q = p->next;delete p;p = q;}tail = NULL;
}int main() {LinkList l;l.Init();int n;cin >> n;l.TailCreateList(n);l.PrintList();l.Delete(3);l.PrintList();l.Insert(99, 2);l.PrintList();cout << l.Get(3) << endl;l.PrintList();cin >> n;l.HeadCreateList(n);l.PrintList();l.Delete(4);l.PrintList();l.Insert(99, 3);l.PrintList();cout << l.Get(4) << endl;l.PrintList();return 0;
}