单链表的实现

#include 
using namespace std;

struct listNode{
	int data; //存放本节点的数据 
	struct listNode* next; //存放下一个节点的位置 
};
 
 
 
void insertNode(listNode *head, int pos, int value) {
	int step = 0;
	listNode* temp = new listNode;
	listNode* node = head; //在后面改变了head的指向,需要先保存初始的head的指向 
	temp->data = value; 	//保存链表头的原始位置 
	while (step < pos) {	//感觉这里需要记忆，比较难理解 
 	head = head->next;
	step++;
	} 
	temp->next = head->next;
	head->next = temp;
	head = node;	
}

void deleteNode(listNode *head, int pos) {
	listNode* node = head; //在后面改变了head的指向,需要先保存初始的head的指向 
	int step = 0;	
	while (step < pos) {
	head = head->next;
	step++;
	}
	listNode *previous = head->next; 
	head->next = head->next->next;	
	delete previous; 	//delete一个指针其实是delete掉它指向的对象，delete掉head->next指向的对象 
	head = node;	
}

bool isEmpty(listNode *head) {
	return head->next == NULL? true : false; 
}

int size(listNode *head) {
	listNode* node = head;
	int count = 0;
	while (head->next != NULL) {
	count++;
	head = head->next;
	}
	head = node;
	return count;
}

//遍历整个链表 
void traverse(listNode* head) {
	listNode *node = head;
	head = head->next;
	while (head != NULL) {
	cout << head->data << endl;
	head = head->next;
	}
	head = node;
}

void clear(listNode* head) {
	listNode* temp;
	listNode* node = head;
	//这里要理解一下 
	while(head->next != NULL) {
	temp = head->next->next;
	delete head->next;
	head->next = temp;
	}
	head = node;
}