C语言 单向链表_c 单向链表 append

/* 1.C语言单向链表 
 * 2.链表的(增,删,查,遍历) 
 * Author: Mr.Long 
 * Date  : 2015-12-1 15:24:26 
 */
#include<stdio.h>
#include<stdlib.h>
 
/* 结构定义 */
struct node {
	int data;
	node *next;
};
 
/* 函数定义 */
void printNode(struct node *head);
struct node* appendNode(struct node *head,int);
struct node* addFirstNode(struct node *head,int);
struct node* findNode(struct node *head,int);
int deletNode(struct node *head,int);
 
int main() {
	
	/* 定义一个head指针,作为链表的头节点*/
	struct node *head = NULL;
	//申请内存空间 
	head = (struct node *)malloc(sizeof(struct node));
	//初始化头结点数据 
	head->data = 0;
	head->next = NULL;
 
	printf("*****************添加节点******************\r\n");
	/* 在链表尾部追加节点 */
	head = appendNode(head,5);
	head = appendNode(head,8);
	head = appendNode(head,4);
	head = appendNode(head,34);
	head = appendNode(head,6);
	head = appendNode(head,9);
 
	/* 添加为头节点 */
	head = addFirstNode(head,12);
	head = addFirstNode(head,61);
 
	printf("添加成功... \n");
	
	printf("*****************查找节点******************\r\n");
	/* 查找指定节点 */
	struct node *a;
	a = findNode(head,34);
	if(a != NULL) {
		printf("查找成功... \n");
		printf("data:%d \n",a->data);
		printf("next:0x%X \n",a->next);
	} else {
		printf("没找到该节点 \n");
	}
	printf("*****************删除节点******************\r\n");
	/* 删除指定节点 成功返回1 失败返回0 */
	int dest = 0;
	bool state = deletNode(head,dest);
	if(state)
		printf("删除[%d]成功... \n",dest);
	else
		printf("删除[%d]失败... \n",dest);
 
	printf("*****************所有节点******************\r\n");
	
	/* 遍历节点并输出 */
	printNode(head);
 
	return 0;
}
int deletNode(struct node *head,int dest) {
	struct node *p = head;
	struct node *lp;
	while(p->next) {
		if(p->data == dest) {
			// 删除操作:将上一个节点的next指向被删除节点的next 
			lp->next = p->next;
			//释放被删除节点的内存空间
			free(p);
			return true;
		}
		//记录上一个节点
		lp = p;
		//移动指针
		p = p->next;
	}
	return false;
}
struct node* findNode(struct node *head,int dest) {
	struct node *p = head;
	struct node *pc = NULL;//临时变量
	 
	while(p) { //当p不为NULL时 
	
		if(p->data == dest) {//找到了指定节点 
			pc = p;
			break;
		}
		p = p->next;	//移动指针 
	}
	return pc;
}
struct node* appendNode(struct node *head,int data) {
	if(data == NULL) return head;
	if(head == NULL) { //若头结点为空,则创建一个节点作为头结点 
		printf("head is NULL \n");
		head = (struct node *)malloc(sizeof(struct node));
		head->data = data;
		head->next = NULL;
		return head;
	}
	/*易错点
	 * 	这里千万注意循环条件是p->next而不是p
	 *  因为当执行到链表尾节点时p已经为NULL
	 *	而当p为NULL时56行的空指针操作会导致程序崩溃
	 */
	struct node *p = head;
	while(p->next) {
		p = p->next;
	}
	struct node *pNew;
	pNew = (struct node *)malloc(sizeof(struct node));
	pNew->data = data;
	pNew->next = NULL;
 
	p->next = pNew;
	/*易错点:
	 *	如果这里返回 p 则链表只保留了最后两项数据
	 *	原因在于47行的while循环移动了p的指针
	 */
	return head;
}
struct node* addFirstNode(struct node *head,int data) {
	struct node *p;
	p = (struct node *)malloc(sizeof(struct node));
	p->data = data;
	p->next = head;
	return p;
}
void printNode(struct node *head) {
	struct node *p = head;
	while(p) { /* 当p不为NUll时 */
		printf("self=0x%X  |  data=%2d  |  next=0x%X\n",p,p->data,p->next);
		p = p->next;
	}
}