单链表的建立、求长、插入、删除、输出和释放 （带头结点）

#include<iostream>using namespace std;typedef struct node{int data;struct node *next;}Node, *List;//建立带头结点的单链表List createList(){Node *head, *p1, *p2;p1 = p2 = head = new Node;//头结点int num;cin >> num;while(-1 != num){p1 = new Node; p1->data = num;p2->next = p1;p2 = p1;cin >> num;}p2->next = NULL; //不可少return head;}int getListLength(List p){int length = 0;while(NULL != p->next){length++;p = p->next;}return length; //不包括头结点}//把element插入到第position个位置List insertNode(List p, int position, int element){int length = getListLength(p);if(position < 1 || position > length + 1){cout << "wrong position" << endl;exit(1);}Node *p1 = p ->next;Node *p2 = p;int i;for(i = 0; i < position - 1; i++){p2 = p1;p1 = p1->next;}Node *s = new Node;s->data = element;p2->next = s;s->next = p1;return p;}List delNode(List p, int num){Node *p1 = NULL, *p2 = NULL;if(NULL == p->next)return p;p1 = p->next;p2 = p; //不可少//注意while中条件的顺序while(NULL != p1 && num != p1->data){p2 = p1;p1 = p1->next;}//注意if中条件的顺序if(NULL == p1)cout << "not been found" << endl;else{p2->next = p1->next;delete p1;}return p;}void printList(List p){while(NULL != p->next){cout << p->next->data << " ";p = p->next;}cout << endl;}//下面采用递归释放（也可循环释放）void releaseList(List p){if(NULL == p->next)delete p;else{releaseList(p->next);delete p;}}int main(){List head = createList();printList(head);int position = 4;int element = 100;head = insertNode(head, position, element);printList(head);int num = 3;head = delNode(head, num);printList(head);releaseList(head);return 0;}